

LIBRARY OF CONGRESS. 

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UNITED STATES OF AMERICA. 














TABLE No 

55 VOLTS. 
















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































TABLE No. 4 

75 VOLTS. 



Lamp 


Feel 


75 VOLTS 


No. IS 


Western t Elpctrician,\Chicago. \ 



























































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































X 


TABLE No. 5. 

1 10 VOLTS. 



I L amp 


110 VOLTS 


Lamp 


Western .Electrician, 











































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































Incandescent Wiring 

H and-Book, 


WITH THIRTY-FIVE ILLUSTRATIONS AND 
FIVE TABLES. 




s'S 

F. B. BADT. 

^ i » 

Late First Lieutenant Royal Prussian Artillery. 

Author of “Dynamo Tenders' Hand-Book “ Bell-Hangers' 
Hand-Book." 



ELECTRICIAN PUBLISHING COMPANY, 

CHICAGO, ILL. 


1889. 






Copyright, 1889. 


BY 


ELECTRICIAN PUBLISHING COMPANY. 


AI.I. RIGHTS RESERVED. 





PREFACE. 


The success which attended the publication of the 
“Dynamo Tenders’ Hand-Book,” and the “Bell-Hang¬ 
ers’ Hand-Book,” induced the author to undertake the 
preparation of a book of practical instructions for incan¬ 
descent wiring. That a demand for such a work exists 
has been amply demonstrated from time to time by numer¬ 
ous letters of inquiry which have been received by author 
and publisher. It has been the author’s object to prepare 
a hand-book containing practical suggestions for workmen, 
and tables of exact data from which sizes of wires, dis¬ 
tances and percentages of loss in conductors could readily 
be computed by those unfamiliar with algebraic formula}. 
To those who wish to study the principles underlying elec¬ 
tric lighting the following works are cordially recom¬ 
mended: “ Elementary Lessons in Electricity and Magnet¬ 
ism” and “Dynamo Electric Machinery ” by Silvanus P. 
Thompson; “Electric Light Arithmetic,” by R. E Day; 
“Magneto Electric and Dynamo Electric Machines,” by 
Dr. II. Schellen; Munro & Jamieson’s “ Pocket-Book of 
Electrical Rules and Tables;” Badt’s “Dynamo Tenders’ 
Hand-Book.” 

The author desires to acknowledge that he is indebted to 
the Manufacturer and Builder and the Western Electri¬ 
cian for several valuable suggestions. 

F. B. Badt. 

Chicago, June, 1889. 



CONTENTS. 


Introductory— page. 

The Multiple Arc System, Chapter I ... 2 

The Three-Wire System, Chapter II .2, 3, 4 

Methods of Running Wires — 

Cleat-Work, Chapter III. 5, 6 

- Moulding Work, Chapter IV.7, 8, 9 

Concealed Work, Chapter V.g, 10, 11, 12, 13 

a. When the Building is Being Constructed.9, 10, 11 

b. In a Completed Building.11, 12, 13 

Location of Safety Devices and Switches— 

The Tree System, Chapter VI.14, 15 

The Closet System, Chapter VII.14, 16, 17 

Safety Devices, Chapter VIII...16, 18, 19 

Switches, Chapter IX. 19 

Splices, Chapter X.19, 20, 21 

Safety Rules, Chapter XI.22, 23, 24 

Insulation and Testing for Faults, Chapter XII. 

24, 25, 26, 27 

Fixtures and Elevators— 

Wiring of Fixtures, Chapter XIII .28, 29, 30, 31, 32 

Wiring of Elevators, Chapter XIV. 32 

Wire Gauges— 

Wire Gauges, Chapter XV.. 33, 34 

General Electrical Data— 

Coulomb, Chapter XVI.. .. 35 

Ampere, Chapter XVII. .. 36 

Volt, Chapter XVIII. 36 

Ohm, Chapter XIX. .36, 37 

Conductors and Insulators, Chapter XX. 37 

Ohm’s Law, Chapter XXI. 38 





















CONTENTS. 


General Electrical Data— Contimied . rage. 

Conductivity, Chapter XXII.. .. 38, 39 

Divided Circuits, Chapter XXIII ... .. 39, 40 

Work, Energy, Power, Chapter XXIV.40, 41 

Calculating Sizes of Wires— 

Plans and Symbols, Chapter XXV.42, 43 

Drop of Potential and Loss of Energy, Chap¬ 
ter XXVI . 43 , 44 . 45 

Practical Rules for Determining Sizes of Wires, 
Chapter XXVII...45, 46, 47, 48, 49, 50, 51, 52, 53 


Safe Carrying Capacity, Chapter XXVIII. .... 

53 , 54 , 55 , 56 

The Three-Wire System, Chapter XXIX.56, 57, 58, 59 
Explanation of Tables, Chapter XXX. .59, 60, 61, 62 


Table No. 1.—Gauges in Circular Mils .. 63, 64, 65 
Table No. 2.—Electric Light Conductors.. — 66 

Table No. 3.—50 Volt Lamps. 

Table No. 4.—75 Volt Lamps. 

Table No. 5.—no Volt Lamps. 





















INTRODUCTORY. 


The several methods of wiring for electric lighting may 
be classified as follows: 

First—The Multiple Arc System. 

Second—The Multiple Series System. 

Third—The Three-Wire System, which is really a com¬ 
bination of the first and second systems. 

Fourth—The Alternating Transformer System. 

These systems are applied according to varying condi¬ 
tions, e. g , for long distances the multiple arc system is 
not used. 

The object of this little book, however, is not to explain 
these systems of wiring, but merely to give practical rules 
for wiring buildings. 

There are only two reliable systems which may be used 
fur wiring residences, offices and buildings generally for in¬ 
candescent lights. These are the multiple arc and the three- 
wire systems. These methods will be explained, and the 
data necessary for the successful wiring of a building for 
incandescent electric lights in accordance with these sys¬ 
tems will be given. It should be mentioned that in the 
alternating transformer system which is used for distributing 
lights over a large area, the high pressure in the mains is 
converted to low pressure in the transformers. The wiring 
from transformers to buildings is done on the multiple arc 
system, so that only a knowledge of the multiple arc and 
three-wire systems is essential to incandescent wiremen so 
far at least as the wiring of buildings is concerned. 

As the multiple series system and the series multiple sys¬ 
tem can be used only on a small scale and under certain 
peculiar circumstances, explanations of the two methods 
will be omitted. The great disadvantage attaching to 
these two systems consists in the fact that it is almost 
impossible where they are employed to insure perfect safety 
against fire, and their use should therefore be restricted 
mainly to outdoor lighting or to places in which there is 
little danger of fire. 


(i) 



2 INCANDESCENT WIRING HAND-BOOK. 


There are also systems by which incandescent lamps are 
run on arc circuits, but the same objection may be be made 
to them as to the multiple series and series multiple sys¬ 
tems. 


Chapter I. 

The Multiple Arc System. 

The multiple arc system of incandescent wiring which is 
also called the multiple system or the parallel system, will 
be readily understood by reference to Fig. I. 

Each lamp in the system is independent of all others, 
and any number of lamps may be switched in or out with¬ 
out interfering with the other lamps, provided the electro¬ 



motive force at the dynamo is kept constant. Only lamps 
intended for a given electromotive force are connected in 
one system; for instance, in a 50-volt system, only lamps 
marked fifty volts should be used, and in a ioo-volt sys¬ 
tem only lamps marked 100 volts should be connected, etc. 


Chapter II. 

The Three-Wire System. 

In the three-wire system two dynamos are joined in 
series, and the lamps are connected between a center or 
neutral wire and the positive and negative wires of the sys¬ 
tem. Fig. 2 represents the plan of this system. 

The advantage of this method lies in the fact that the 
electromotive force is double that employed in the multiple 
arc system, while the current strength is only one-half of 
that of the latter system. This advantage is evident when 
it is stated that the mains require practically only three- 
eighths as much copper as is needed in the mains of a 






THE THREE-WIRE SYSTEM. 


3 



Fig, 2. — Three-Wire System, 























4 INCANDESCENT WIRING BAND-BOON. 


multiple arc system supplying the same territory. For 
example, if 1,000 pounds of copper were required in a 
multiple arc system of wiring, for say 200 lamps, only 1,000 
x % — 375 pounds, would be necessary in the three-wire 
system. (Compare Chapter XXIX.) 


METHODS OF RUNNING 
WIRES. 


i 


After the system of wiring has been decided upon the 
several modes of running the wires are to be considered 

Chapter III. 

Cleat-Work. 


The most common and cheapest method of running 
wires is by cleat-work. The wires are entirely exposed, 



Fig. 3. — Two-Wire Cleat. 



11 



Fig. 4. — Wires in Separate 
Holes. 

( 5 ) 


Fig. 5. — Protection of 
Wires, 
































6 INCANDESCENT WIRING HAND-BOOK . 


being merely secured at short intervals by hard wood 
cleats. Wires are frequently fastened in this way in stores, 
where a long straight run is obtained with short branches; 
waterproof insulation is usually employed. This system 
is usually followed where the appearance of the wires is 
of no great consequence; for example in mill and factory 



Fig. 6. — Three-Wire Cleat. 

wiring, cleat-work is usually the most desirable method 
of running wires, as it admits of ready access to conduc¬ 
tors in case it is necessary to change the location of the 
lamps. 

Figs. 3, 4, 5, 6 and 7 show the use of cleats. Fig. 3 
shows a familiar form of cleat. Where the positive wire 



crosses the negative, the extra protection of rubber tubing 
is required to prevent any danger from short circuits, Fig. 5. 

In passing through a wall, each wire should be inserted 
in a separate hole, lined with a hard rubber, glass or por¬ 
celain tube, Fig. 4. 

Fig. 6 represents a cleat for the three-wire system. Fig. 
7 shows the use of three-wire and twp-wire cleats in the 
three-wire system. 































METHODS OF RUNNING WIRES. 


7 


Chapter IV. 

Moulding Work. 

Moulding work, so-called because the wires are covered by 
wooden mouldings, is more expensive, both for material 
and labor than cleat-work, but is much neater in appear¬ 
ance. It is applicable in all places that are reasonably freq 
from moisture. In damp places the cappings and mould- 
ings are both apt to warp and the appearance of the worl< 
will be greatly marred. 

It is not usually desirable to attempt to match the wood¬ 
work of an ordinary room by using, for example, ash, oal$ 
or cherry mouldings. Such mouldings are hard to manage, 



Fig. 8. — Plain Two-Wire Moulding. 

as they warp and twist badly while seasoning after they 
have been put in position. They are also hard to cut and 
fit, and unless the wireman possesses considerable skill as 
a carpenter, the result will be a piece of work that in the 
end is more expensive and not as neat as if pine or white 
wood had been used. 

These latter woods do not warp as readily, and when 
warped are much more easily held in place. As there is 
a possibility that the location of the lamps may be changed, 
the cappings should be secured with round head brass 
screws. 

Wires are frequently hidden under strips of moulding 
that can serve as chair rails, or, under what appears to be 
an extra row of beading just above the base-board or 
wainscoting, or below the cornice, of a room. A chandelier 
in the center of a handsomely papered or frescoed ceiling 
can be reached by dividing the ceiling into panels by 
mouldings, under one of which the wires can be run, and 
by use of rosettes ojr other ornaments, as the taste of 












8 INCANDESCENT WIRING IIAND-BOOIC. 


the architect may suggest, often very pleasing effects can 
be produced by what would at first seem likely to be any¬ 
thing but ornamental. 

Fig. 8 represents a cross-section of wood moulding. The 
lower part is fastened to the wall or ceiling. The positive 




Fig. ii. — Three-Wire Moulding. 


wires are put into one groove, the negative wires into the 
other and the cover is then screwed on. Care must be 
taken that nails or screws do not touch the wires. 

































METHODS OF RUNNING WIRES. 


9 


Figs. 9 and io represent fancy picture mouldings which 
are also used as wire mouldings. The use of such mould¬ 
ing in new buildings has recently become very frequent. 

Fig. ii represents moulding as used for the three-wire 
system. 


Chapter V. 

Concealed Work. 

To secure the best results, as far as appearances are con¬ 
cerned, wiring should be concealed. To conceal wires in 
a building that has already been finished and furnished 
requires no little skill and care on the part of the workmen. 
The difficulties which, of necessity, workmen encounter in 
wiring a finished building are so well known that it is almost 
superfluous to add that it is very much cheaper to wire a 
structure while it is building. If this, for any reason, is 
not desirable the architect should be instructed to leave 
such openings and holes in the walls and floors as will facil¬ 
itate the work if done subsequently. 

a. Concealed work in a building in course of construction. 
The best time for doing concealed wiring is when the build¬ 
ers have finished boarding-in and have not yet begun 
lathing. The cost of wiring at that time is very much less, 
sometimes not more than one-half as much as in the finished 
structure. In occupied houses, however, the inconvenience 
caused by putting in wires can be made slight. Little or 
no dirt need be made; there need be no hammering or 
pulling away plaster, laths and floors. The most delicate 
finishing should in no way be injured by the workmen. 
When the job is completed, and well done, it should be 
difficult to discover evidence that the work has been done. 

To do concealed work properly requires cons'derable skill 
and experience. Such work therefore should be intrusted 
only to reliable and responsible concerns. Unfortunately, 
any man who ever fastened a piece of wire for a bell-pull 
regards himself as an expert also for incandescent wiring. 
A great number of even important contracts have been 
executed by men of this kind with the result that, after the 
expenditure of considerable money by owners of houses it 
has been necessary to condemn the whole system, as the 
wires had invariably been improperly placed. 

Before work is commenced a building should be thor¬ 
oughly inspected and plans formed for running the wires. 


IO INCANDESCENT WIRING HAND-BOON. 


If the building is in process of construction the wiring con¬ 
tractor must of course use every argument to induce the 
architect to make provision for the electric light wires. The 
following will serve as a suggestion: 

Whether the plaster is laid directly on the bricks or the 
wall is furred and lathed, passages should be left by 
the builders along its surface where necessary, by recessing 
a course of brick, say three-fourths to one inch. Vertical 
openings are less easily left; still, by making use of the 
space between a door casing and an adjacent wall and by 
making an opening to the floor above or below, the wires 
can be readily run. The passage of wires from one room 
to another ought to be provided for by leaving openings 
through the partitions at suitable places between ceiling and 



floor. Wires can be easily secured to the floor timbers after 
passing from the walls to positions over the chandeliers. 

If the building is fire-proof a space of an inch or two 
will generally be found between the floor boards and the 
brick or concrete beneath. If wires are not put in at once, 
one of the spaces between the nailing strips to which the 
floor is secured, over the chandelier in the room below, 
should be carefully kept free from dirt and closed with 
pieces of wood placed in the form of a “V,” with the apex 
near the place for the opening in the ceiling to be made in 
the future. If the little device shown in Fig. 12 is used 
when building, at the cost of a few cents, and one of the 
spaces is reserved for the wires instead of all being made 
receptacles for rubbish and blocks of wood, hours of labor 
would be saved in the future when the tedious process of 
“fishing” wires through the openings is undertaken. Such 


METHODS OF RUNNING WIRES . 


ii 


precautions, too, will often save the cutting or removal 
of parts of handsome floors which may prove insuperable 
obstacles to the wiremen. 

Mouldings of the types shown in Figs. 9 and 10 facili¬ 
tate greatly the running and distribution of wires and will 
prove very convenient in making auxiliary branches for con¬ 
cealed wiring. 

It is frequently convenient to use chases about four 
inches square, purposely left in the walls, to carry wires for 
room or floor distribution. The location of such chases 
should be carefully considered with reference to lateral 
openings. Each section of the building can in this way be 
provided with “risers,” which, with the methods already 
described, form a perfect system of distribution- applicable 
to almost any building. “Pockets” or openings of sufficient 
size, say 18x12 inches, must be left in the flooring opposite 
the wall chases to allow connection with “cut-outs” and 
“branches,” and also for convenience in “fishing.” A 
proper “cut-out” box should be placed in the wall near the 
chase, to which the wires are run before passing under the 
floor. 

From the foregoing it would seem plain that, in order to 
secure the best results for the least money, it is necessary 
the architect should make ample provision for electric 
wiring. With proper preparation, made at an almost insig¬ 
nificant cost, the difficulty of electric light wiring can not 
only be greatly diminished, but the cost of the work to the 
owner can also be greatly reduced. If a wiring contractor 
is assured that intelligent provision has been made for his 
work; that convenient openings have been left through 
.walls and floors with as much care as for steam or gas pipes; 
that he will not have to devote days to drilling brick or stone 
walls, or taking up and relaying floors, it is hardly necessary 
to say that he can afford to charge much less for his work. 

The importance of this too often neglected matter 
to architects, owners and builders, is tod obvious to require 
further comment. 

b. Concealed work in a completed building. In old 
buildings, especially those which are not fire-proof, the 
‘ ‘ fishing ” of wires will proceed with few obstacles. The fol¬ 
lowing instructions may give beginners some valuable hints: 

HOW TO FISH WIRES. 

Punch a hole through the plastering at the required posi¬ 
tion, being careful that there is no studding at that, place. 


12 INCANDESCENT WIRING HAND-BOON. 


Use a brad-awl and cut the hole large enough to permit the 
running of the wires. With a short length of small brass 
spring wire, push, through the opening a few inches of num¬ 
ber 19 double jack-chain such as is used for general fish¬ 
ing purposes, first having connected the end of the chain 
with a piece of heavy linen thread. Run out the thread 
between the laths and the outside wall until the chain 
touches the floor beneath; move the thread and locate the 
chain by the sound; bore a hole through the base-board or 
floor, as the case may be, toward the chain. Use a two or 
three-foot German twist gimlet With a small brass spring 
wire bent at the end in the shape of a hook, fish for the 
chain and draw it out. At the other end of the thread 
attach the wire and draw it through with the thread. Pass¬ 
ing under the floor bore a second hole through the floor as 
near the other as possible. Run into this a piece of snake 
or fishing wire which is ^5x1-64 inch steel wire, with a hook 
at the end, until it comes to an obstruction. Locate the 
obstruction by sound. In running wires under the floor¬ 
ing first carefully examine all parts and find the direction 
in which the beams and timbers run, and run the wires 
parallel with these. After locating the end of the fishing 
wire see if the obstruction is a timber; if so find the center 
and bore from the middle diagonally through it in the 
direction of the fishing wire. Drop the jack-chain and 
thread through the hole; fish for it and draw it through hole 
number 2; attach the insulated wire and draw it back. Start¬ 
ing hole number 3, bore hole number 4 diagonally through 
the timber in the direction in which the wire is to be run, 
making holes 3 and 4 form an inverted “ V ” through the 
timber. Run the fishing wire through hole number 4 
until it meets an obstruction. If at the end of the room 
bore through the floor, drop the chain, fish it out, attach 
wire and draw it home. Putty up holes after having done 
with them, or, in case of hard finish, plug them up with 
wood. 

In lightly built houses it is often found easier to take off 
the moulding above the base-board and run the wire under 
it. In such cases care should be taken to break off the old 
nails, as any attempt to drive them out would cause a bad 
break. In closets and around chimneys it is usually found 
easy to work. A ‘ ‘mouse” or lead weight attached to a string 
may often be dropped from the attic to the cellar ceiling 
through the space outside the chimney. It is well before 
starting on a job to examine carefully the whole house and 


METHODS OF RUNNING WIRES. 


^3 


find the easiest places to run in. When it is necessary to take 
up carpets be sure and put them down again as quickly as 
possible, in order to reduce to a minimum the inconven¬ 
ience to residents. 


LOCATION OF SAFETY DE¬ 
VICES AND SWITCHES. 


Having determined which of the three methods of 
wiring, “Cleat,” “Moulding” or “Concealed Work,” shall 
be followed in the different parts of the building, the wire 
contractor must decide on what general plan the work shall 
be done. 

Ordinarily one of two plans is adopted, either what may 
be termed the “Tree System,” or the “ Closet System.” 

Both systems are applicable to all cleat, moulding and 
concealed work, and to either the multiple arc or the three- 
wire system. 

Usually, however, cleat-work and moulding-work are done 
on the tree system and concealed work on the closet sys¬ 
tem. 


Chapter VI. 

The Tree System. 

Fig. 13 represents the tree system of multiple arc wiring. 

The system is easily understood. All branch lines con¬ 
nect to the main wires as branches to the trunk of a tree. 
Whenever the size of a ware changes, or a branch is run 
from a main, a safety device is inserted. Switches are 
located in a branch wherever necessary or especially con¬ 
venient. These safety devices and switches will be further 
considered in a subsequent chapter. 


Chapter VII. 

The Closet System. 

Often in concealed work and sometimes in cleat and 
moulding-work it is not desirable to have the cut-outs and 
switches scattered over the ceilings and walls of the sev¬ 
eral rooms and halls as would be the case if the tree sys- 

(M) 



safe tv de vices and S WITCHES. i 5 



Fig. 13 — Tree System. 
































































16 INCANDESCENT WIRING HAND-BOOK . 

tem were adopted. It is, therefore, preferable whenever 
practical to group the cut-outs and switches in dry and easily 
accessible places. An excellent way, for example, is to place 
a neat box in the wainscoting. All branch wires lead to 
this box, and nothing appears except groups of cut-outs 
and switches- This box should be provided with lock and 
key. If the building is in course of construction recesses 
should be left in partition walls for branch wires and boxes. 

Fig. 14 represents the closet system. 

Fig. 15 shows a box with cut-outs and switches located 
in a partition wall with several branch wires fished under 
the floor and through a recess in the partition wall. 

The boxes containing the cut-outs and switches should 
be lined with some non-combustible material such as asbes¬ 
tos cloth of a thickness of at least one-sixteenth of an 
inch. The outside of the boxes should be painted with 
asphaltum or other insulating paint. 

It is not necessary of course that each room and passage- 
should have its own switch as is sometimes required. Key 
sockets can generally be used to advantage for brackets and 
small chandeliers, except where the lamps are inaccessible. 
Each floor can be controlled by a switch conveniently 
placed in a hallway, the lights in which should be on a sepa¬ 
rate circuit. Long passages, cellars seldom used, etc., 
should have switches placed at their entrances so that they 
may always be lighted when a person enters or leaves them. 
The number of modifications which may be made in the. loca¬ 
tion of switches is unlimited, and special arrangements can 
always be devised to suit the convenience or whims of own¬ 
ers of houses. With the exception of these special 
switches it is generally advisable to locate the switches and 
cut-outs in closets as described. 

Chapter VIII. 

Safety Devices. 

Strips of an alloy wbich fuses at a low temperature are 
used as safety devices, or plugs, in incandescent wiring. 
The cross-section of the plug must be of such size that it 
will melt before the wire it protects becomes dangerously 
warm. Hence, the sectional area of the safety plug 
depends upon the cross-section of the wire to be protected 
and not upon the number of the lamps. Safety plugs are 
not supposed to protect incandescent lamps from an excess 




* 



% 

# 




Fig. t 









































































18 INCANDESCENT WIRING HAND-BOOK . 


of current, but to protect buildings from fire by preventing 
any part of the electric light conductors from carrying an 
excess of current, and thus becoming too hot. The mark¬ 
ing of safety plugs with the number of lamps they can 
carry has led many a wireman to conclude that the plugs 



Fig. 15.— Distributing Closet. 

are put in for the protection of a certain number of lamps. 
The marking of the plugs simply expresses their carrying 
capacity in 16 candle power lamps instead of in amperes. 

The blowing-out of safety plugs is very often caused, not 
by an excess of current, but by poor contact between the 
safety plug and the safety plug-holder. A poor contact, of 




























SAFETY DE VICES AND SWITCHES . ig 


course, will cause heating, which will gradually fuse the 
metal at one end. 

A multitude of safety devices or ‘' cut-outs ” has been 
invented. They entirely eliminate the element of danger if 
a sufficient number is used, and if work is properly done, 
when a building is first wired. 

Wherever the size of a wire changes, or a branch is run 
from a main to supply a smaller conductor, fusible plugs or 
“cut-outs ” are employed. These protect the small wires 
from a dangerous amount of current that would tend to 
pass through them in the event of a “ gross” caused by 
the accidental contact of bare wires of opposite polarity. 
Too strong a current will, of course, fuse the cut-out and 
break the circuit. Large or small clusters of lights in 
chandeliers are protected in the same way by a small device 
often called a “ bug.” This is a small fusible wire secured 
to an insulating block of wood or porcelain, and concealed 
under the canopy of the fixture or chandelier. Only 
double-pole safety cut-outs should be used, i. e., each 
branch, etc., should be provided with a cut-out in both the 
out-going and the return wires. 

Chapter IX. 

Switches. 

A switch is a device used to break or make circuit, or, in 
other words, to cut off the current in certain convenient 
places from a number of lamps or cut them in again. The 
switches should be so constructed that they will open and 
close the circuit very quickly and spark but little. This is 
accomplished by having the switch so arranged that the 
hand will start, it,— while a powerful spring throws the 
switch open or closes it immediately. The contact should 
be sufficient to prevent heating at these points. 

Switches are either of the single or double-pole break 
type. Double-pole switches are preferable as they allow 
both the cutting-out of a faulty circuit and the testing for 
faults in the shortest time. 

Chapter X. 

Splices. 

When a splice in a wire is necessary, it should 'be made 
after the fashion of the American telegraph splice, Fig. 16. 


20 INCANDESCENT WIRING HAND-BOOK i 


It should be perfectly cleaned, firmly soldered, and after¬ 
ward well taped with insulating tape. 

This splice can easily be made in wires not larger thafi 
No. 3 B. & S. gauge. In larger wires splices are made 
in the manner shown in Fig. 17. 

Fig. 18 shows the method of attaching a small branch 
wire to a larger wire. 

Joints must always be soldered. Use acid for soldering 
and not resin. The reason is best given in the following 



Fig. 16. — American Telegraph Splice. 


abstract from a letter written by an inspector of the Boston 
Fire Underwriters’ Union: ‘T am often asked why I pre¬ 
fer acid to resin to solder joints in electric light wires. I 
do not prefer it, but think that we get better results from 
acid than resin. It is safe to say that only one out of ten 




Fig. 17. — Method of Splicing Heavy Wires. 


knows how to make a good joint with resin, or, if they do 
know, they .will not take the trouble. The secret of joints 
made from resin is a perfectly clean surface. This, of 

























SAFETY DE VICES AND SWITCHES. 21 


course, requires some care, while with acid, if the wire has 
any oil or grease, or any of the insulation which the line¬ 
men have failed to scrape off, the acid will do the work 
which the workmen (by name, but not by nature) have 
failed to do. I have learned from experience that the wires 
eaten off by acid are so few that the danger from fire from 
such cases is less than those from poor joints with resin. 
I hope that some time in the future we shall have men that 
we can depend on to make joints with resin.” 

Never apply tape to unsoldered wire splices; the rubber 
on the tape will cause corrosion and so make poor a contact 
which at first was good. 

The joints or connections in waterproof wires should be 
made waterproof also. This is done in the following way: 
After having cleaned, spliced and soldered the wires 
properly, cover the joint with hot Chatterton’s compound, 
holding it between the fingers, to almost the total thickness 
of the insulated wire. Cover it with kerite tape and give 



Fig. 18.— Method of Tapping. 


it a second thin coating of hot compound, or hotasphaltum, 
and then give it a second coat of kerite tape. Hot liquid 
asphaltum should be used instead of compound, where 
there is danger from sewer or illuminating gas, which often 
permeates the soil and basements of houses in large cities. 
Frequently waterproof wires with an outside braiding or 
taping are used. This outside cover is intended simply as 
a protection for the real insulation or dielectric from 
abrasion. When joints are made or branches are taken off 
the mains, this braiding or taping must not reach into the 
insulating material of the splice, as it would practically 
form a path for the moisture to penetrate the insulation to 
the wire. This point, although of the greatest importance, 
is very often overlooked, and its neglect causes frequent 
break-downs of the insulation of joints. 














22 INCANDESCENT WIRING HAND-BOOK. 

Chapter XI. * 

Safety Rules. 

1. Whenever wires pass through walls, roofs, floors or 
partitions, or there is liability to moisture, abrasion, or ex¬ 
posure to rats and mice, the insulation must be protected 
with rubber, stoneware or some other satisfactory material. 

2. Wires entering buildings must be wrapped with tape, 
and tent in such a manner that water will be prevented 
from entering the building. 

3. All wires passing over or under steam, gas or water 
pipes,must have good insulation between them. Blocks of 
wood are the most desirable. This rule also applies to 
foreign wires; they should be treated the same as pipes. 

4. Soft rubber tubing is not desirable as an insulator. 

5. Wires should go over water pipes, where it is possi¬ 
ble, so that the moisture will not settle on them. 

6. Where incandescent wires enter buildings, they must 
have double-pole safety catches as near the entrance as 
possible. 

7. Main wires must not be less than two and a half 
inches apart, except where they are in grooves. 

8. All wires that are fished over the ceiling or in the 

walls, must have waterproof insulation. This rule also 
applies to wires covered with moulding, or concealed in any 
manner. ^ 

9. Where underwriters’ wire is used, it must be in plain 
sight on the walls or ceilings. 

10. Care must be taken to avoid placing wires above 
each other in such a manner that water could make a cross 
connection. 

11. Wires located in damp places, for instance in pack¬ 
ing houses or breweries, must be run on glass or porcelain 
insulators of suitable form. 

12. Conducting wires leading to each important branch 
circuit, must be provided with an automatic safety device, 
capable of protecting’the system from any injury due to an 
excessive current of electricity. These devices must be 
proportioned to protect the smallest wires in the loop to 
which they are attached. 

13. On all loops of incandescent circuits, safety catches 
must be used on both sides of the loop, and switches on 
such loops should be double-poled. 

14. Ceiling blocks that are used on pendant drops 
must have safety fuses in them where flexible cord is used; 


SAFE TY DE VICES AND SIVITCHES. 23 


cord should have a knot tied in it with the knot on the top 
side of the block, so that the strain will cojne on the knot 
instead of on the connection; and where it is possible, a 
knot should be inside of the socket, the same as the block. 

15 The small wires leading to each lamp from the 
main wires must be thoroughly insulated, and if they are 
separated or broken, no attempt must be made to join them 
while the current is in the main wires. 

16. When wires are put on gas fixtures, the fixture 
must be insulated from the main pipe, and the insulating 
joint used for this purpose must be made so that the sedi¬ 
ment in the gas will not form a connection over the insu¬ 
lating material. 

17. Chandeliers or brackets attached to any ground con¬ 
nection must have insulating yokes or couplings on them. 
Individual insulation of lamps at the sockets is not allow¬ 
able except on brackets in special cases. 

18. The use of metal staples for fastening wires is not 
permissible under any circumstances. 

19. In rooms where explosive gases may develop, or 
where the atmosphere is very damp, the incandescent lamps 
should be inclosed in vapor-tight globes. Switches are not 
permitted in places filled with explosive gases (breweries, 
distilleries), as the spark at make or break might cause an 
explosion. Fusible safety plugs must be inclosed in air¬ 
tight non-combustible cases. 

ALTERNATING TRANSFORMER SYSTEMS. 

20. Transformers or converters on alternating circuits 
must be outside of buildings, and must be placed high 
enough from the roof to prevent possible injury to firemen. 
Inside wires should be treated as any other incandescent 
circuits. 

ABSTRACT OF CHICAGO SAFETY RULES. 

No plant shall be run without a certificate of inspection 
from the superintendent of city telegraph. 

The insulation resistance of each circuit supplied by 
separate feeders or mains, must measure at least 100,000 
ohms. 

.The use of underwriters’ or similab wire, is not per¬ 
mitted. 

The inspector’s fee is one dollar for each horse power, 
ten sixteen candle power lamps being 1 .allowed for one 
horse power. 


24 INCANDESCENT WIRING HAND-BOOK. 

The plant cannot be legally altered after inspection, 
without first notifying the city electrician. While the 
plant remains in the same condition as at the date of the 
certificate, that document is valid. 

Violation of any of the above requirements subjects the 
party so transgressing to a fine of from $50 to $100 for 
each day the infraction is continued. 


Chapter XII. 

Insulation and Testing for Faults. 

When wires are being put up they should from time to 
time be tested for short circuits and grounds. If the 
building is being constructed, close watch must be kept on 
other artisans, especially on carpenters,plumbers and gas fit¬ 
ters These workmen usually have no idea of the meaning 
of insulation, and seem to delight in cutting wires, injuring 
costly insulation and perpetrating other malicious mischief 
generally. 

It has been shown in the foregoing pages how wires 
should be put up, and the abstracts of the safety rules 
ctearly indicate the required standard of insulation. On this 
subject Prof. J. D. F. Andrews very pertinently says in 
a paper recently published: 

“The conductor is copper, and the most widely adopted 
insulation is India rubber in many modified forms. The 
insulated conductors are usually protected and held in posi¬ 
tion by wooden casing. We need hardly question the 
object of the conductor, but what is the object of the in¬ 
sulation? The conductors, if held in good, dry, wood 
casing only, would be protected from interference. Its 
object is to meet one of the worst contingencies—moisture 
or water, which is an ever-working evil on electric light 
wires. If you place a copper wire in water with electricity 
passing along it, the copper will be removed electrolytically 
from the part of the wire where the electricity enters, and 
deposited where it leaves. The same process goes on 
where uninsulated or badly insulated electric light wires lie 
in water, or surrounded by moisture. Even though no 
electricity is flowing through a copper wire exposed to 
moisture and the atmosphere, it is acted upon chemically. 
The result of the electrolytic and chemical actions on 
electric light wires is to thin them and make them insuffi¬ 
cient for carrying the current, and consequently they be- 


SAFETY DEVICES A AW SWITCHES. 25 


come heated. Or the result may be that when the wire is 
eaten through an electric arc is produced. This effect or 
fault is called an opening circuit, and is about the most 
difficult and dangerous fault to contend with. It is usual 
to lay the electric light leading wire in a groove in the 
casing neighboring and parallel to the return wire. Water 
often saturates the casing between them, and when the in¬ 
sulation is poor the electricity will pass through the 
moistened wood and char it, often setting it in flames. 
Faults such as this where a great leak is taking place 
between the wires are called partial short circuits, and are 
equally difficult to avoid and as dangerous as opening cir¬ 
cuits. The study of the insulation of the wires is therefore 
obviously of great importance. The next contingency 
that has to be contended with is mechanical damage. 
The wires being more or less flexible and the covering 
soft, they are easily damaged. This difficulty is usually 
met by casing the wires in wood, and, it being necessary to 
employ two conductors for electric lighting, the casing has 
two grooves, one for each conductor, a cover being fixed 
over them. Wood casing has the disadvantage of harbor¬ 
ing moisture. Another method of protecting the wires is 
that of sheathing them with an outer covering of wire. 
This method protects the wires much more effectually than 
casing, and does not harbor moisture. Iron pipes have 
been used in many cases,, and are an excellent protection; 
but moisture collects in them, and if there should be a 
fault in the insulation it is sure to find it. There is another 
fault besides the opening circuit and partial short circuit 
not yet touched upon, namely, a dead short circuit, or a 
direct contact between the opposite conductors. This is 
the most frequent fault, and if it were not that there is a 
simple appliance called a fuse to meet it, it would also be 
the most dangerous fault. Short circuits usually happen 
in the fittings where the opposite conductors are necessarily 
brought nearer each other, and at these points the insulation 
is generally much thinner and poorer. Short circuits also 
often happen where the wires cross, and frequently by con¬ 
tact with gas and water pipes, which make very compli¬ 
cated faults because the two wires usually touch the pipes 
a distance apart,” 

The insulation resistance between wires and earth must 
be as high as possible, and each branch should be tested 
separately, while the work is in progress. 

The wireman of course, can not as a rule afford to buy an 


26 INCANDESCENT WIRING HAND-BOOK. 


expensive testing set and measure the actual insulation resist¬ 
ance. lie can however, easily obtain a magneto or a 
detector galvanometer, and by means of it, test through a 
resistance of even more than 15,000 ohms and thus locate 
the worst faults in the insulation. 

A testing set designed especially for incandescent wire- 
men, linemen, dynamo tenders and bell-hangers consists 
of a highly-polished wood box containing a small dry gal¬ 
vanic cell, a detector galvanometer of 500 ohms’ resistance, 
a contact key, and two binding posts. The box is so 
arranged that by detaching two hooks the connection 
between the cell, galvanometer and key can be easily in¬ 
spected. There is in the upper part of the box space 
enough to carry wires to be attached to the binding posts 
and the object to be tested. The galvanometer, key and 



Fig. 19 —Connections of a Testing Set. 


binding posts are mounted on the upper surface of a little 
shelf which divides the box into two parts. The lower 
part contains the dry cell. The center shelf slides in 
notches so that by opening the bdx entirely the whole 
centerboard with galvanometer and cell may be pulled out 
for inspection or repairs. As the battery is dry the box 
may be handled and carried in any position without the 
least danger of damaging it. 

Fig. 19 explains the connection of the little instrument. 
C is the dry cell. K is the contact key. X is the contact 
point below the key. G is the galvanometer. B B are the 
binding posts of the instrument. 

The object to be tested is connected to the two binding 
posts B and B, and then the contact key is pressed down. 
























SAFETY DEVICES AND SWITCHES. 27 


If the needle deflects, there is a current passing through 
the circuit; if the needle does not deflect, there is no cur¬ 
rent passing. 

Before testing, the instrument should be put on a level, 
and be turned until the needle points to o. The greater the 
deflection the greater the current which passes through the 
galvanometer. The resistance of the coils of the standard 
galvanometer in this set is 500 ohms. They are made of 
any resistance, however. One cell will deflect the needle 
even through a resistance of 15,000 ohms. If, for instance, 
the insulation resistance of a wire should be tested, one 
binding post is connected by means of a wire to the bare 
copper wire, while the other binding post is connected to 
“earth.” Any gas pipe or water pipe, which runs into the 
ground maybe used as “earth.” Care should betaken not 
to use a waste pipe, or any pipe which does not run into 
the ground as “earth.” 


WIRING FIXTURES AND ELE¬ 
VATORS. 


Chapter XIII. 

Wiring of Fixtures. 

When a building is equipped with incandescent lights, it 
is frequently desirable to attach the lamps to chandeliers or 
other metal fixtures which may be provided. 



Fig. 20. — Grounding on Gas Fixtures. 


The fixtures may be of three kinds, viz., those designed 
for electric lights only; those designed for gas only; and 
those which may be used for either or both gas and electric¬ 
ity, and are called combination fixtures. 

When the incandescent light is introduced in old build¬ 
ings, it will be frequently necessary to adapt the gas fixtures 
to the new method of lighting. Special pains must then be 
taken to keep up a good insulation. 

The wires having been brought to all gas outlets, it is next 
necessary to insulate all fixtures from each other and from 
ground by means of insulating joints. If the fixtures 
were not insulated, the grounding of a wire on one fixture 

(28) 














FIXTURES AND ELEVA TORS . 


29 


would necessarily ground the whole system; furthermore, if 
a positive wire on one fixture and a negative wire 
on another fixture should become grounded, the gas 
pipe connecting the two fixtures would constitute a short 
circuit between the two poles of the dynamo. Fig. 20 
explains this clearly. ^The diagram also shows that in such 
a case, single pole safety fuses would constitute no protec¬ 
tion. Double pole safety fuses should always be used. 
The use of single pole safety fuses without insulating joints 
at the base of the fixtures may result in the burning of 
holes in the gas pipes, followed by the escape of gas, and 
ultimately by_ the ignition and explosion of a dangerous 
mixture of gas and air. The wires must be kept as far from 
gas pipes as possible. The combination of escaping gas 
and grounded wires is very undesirable. 

Insulating joints are of many sizes and various patterns, 
the design of each being determined by the special use to 
which it is to be put. All insulating joints, however, con¬ 
sist of two pieces of iron or brass fastened together in 
some way. but entirely insulated one from the other. The 
metal parts are threaded. Both threads are female usually, 
one to receive the gas pipe outlet, the other the iron chande¬ 
lier stem. The insulating material consists of either vul¬ 
canite or compressed paper fiber; the latter is superior as it 
makes excellent and durable gas-tight joints, the fiber 
shrinking but little when tested by time. The construction 
of the joint should be such that no sediment formed 
by condensation, or chemical combination of the elements 
composing the gas, can collect and form a short circuit 
across the insulating material. In ordering insulating 
joints the purchaser should state the diameters of gas out¬ 
lets and fixture stem, and should explain whether gas, com¬ 
bination or electric light fixtures are to be used; whether 
the joints are to be attached to the gas outlet or are to be pro¬ 
vided with tripods; and whether the joints are intended for 
a chandelier or a wall bracket. 

Gas attachments for incandescent lamps are used for 
fastening lamps to the arms of a gas fixture. This attach¬ 
ment generally consists of a narrow strip of metal, com¬ 
monly brass, provided at one end with a small nipple for 
attaching the lamp socket; the other end is flat and through 
it a hole is punched to permit clamping directly under the 
gas pillar when it is screwed down, thus making a very 
simple but nevertheless a very neat looking fixture. 

Insulating each lamp socket separately from its attach- 


30 INCANDESCENT WIRING HAND-BOON. 


ment by means of a small rubber thimble has of late also 
become customary, and is considered an excellent precau¬ 
tion as too much care can not be taken in maintaining good 
insulation throughout. The insulating thimble alone, 
should, however, never be considered sufficient, without an 
insulating joint, and in every case where lamps are attached 
to any metal supports the fixtures should be insulated from 
the latter. 

Brass rings are often fastened around iron posts or 
columns to hold a circle of incandescent lights. They 
should always be thoroughly insulated from the columns. 
Fixtures attached or fastened to iron girders should be insu¬ 
lated. Insulating joints should be examined occasionally, 
and the clamping screws tightened, to prevent any possible 
leakage of gas on account of shrinkage of the insulating 
material. 

A gas fixture to be properly wired must be taken down 
from its support, a cap being temporarily screwed on the 
pipe to prevent the escape of gas. All the wires on a 
fixture should, if possible, be concealed between the iron 
body and the metal covering or shell which is generally 
made of brass or bronze If sufficient space cannot be 
found there, it Is often possible to make room for the wires 
by substituting smaller iron stems in the chandelier body, or 
by increasing the size of the shell. The wire in the fixture 
should be left slack so that at any small turn or twist the 
fixture will not break the wire or cut or injure its insulating 
covering. Care must be taken, too, where the wire passes 
over any sharp bends or burred edges. File away as much 
as possible of the rough metal and use soft rubber tubing 
or wrap the wire well with tape to prevent injury to the 
insulation. 

To pass the rings and other sections where there is not 
sufficient space, bore through with a small monkey drill, or 
punch a hole with the brad-awl, and file off sufficient metal 
to allow an exit; if necessary run the wire through and over 
the obstruction. The wire employed must always be of the 
best insulation, and must not be too thick, as the space is 
usually very limited. When it is utterly impossible to con¬ 
ceal the wires, or when the job is to be done very cheaply, 
outside wiring must be resorted to. Here duplex wire can 
be very advantageously employed, the color of the covering 
matching as nearly as possible that of the fixture. 

The wire should be held in place by means of a few 
turns of small insulated wire of similar color around the 


FIXTURES AND ELEVATORS . 


31 


arms of the fixture, and these as well as the wire itself 
should be glued to the fixture by a little shellac varnish. 
In this way the wire will be held firmly in place and if the 
work is well done it will often be quite difficult to find any 
indication that the fixture has been wired on the outside of 
its shell. The joints or hinges of a swing bracket must be 
bridged over with a wire loop in the shape of a spiral of 
a size sufficient to prevent interference with the action 
of the bracket. 

A canopy which slides over the outside shell and is pro¬ 
vided with a set screw to hold it in any desired position on 
the chandelier, will hide from v.ew both the insulating 
joint and the “bug” or chandelier safety plug with which 
each fixture should be provided.. (Compare Chapter YI 11 ) 
It will also catch any molten fuse metal, and will always 
form an ornamental finish to the entire fixture. 

Fixtures intended for electric lights only are the easiest 
and most simple to wire, as special provisions are always 
made for this purpose. If the fixtures are not attached to 
any system of gas piping or other metal supports, the mat¬ 
ter of suspending them is very simple; iron tripods only are 
required to fasten them to walls or ceilings. If they are to 
be attached to such a system of piping, whether connected 
to the gas mains and containing gas or not, the precau¬ 
tions already noted must be taken to insulate each fixture. 
A special insulating joint is made for this class of fixtures 
which serves also as a cap for the gas pipe. 

Combination fixtures are arranged to allow the use 
of either gas or electric light, as there are two separate sets 
of arms or piping, one for gas, the other for electric lights. 
They are usually wired by the manufacturers and sold com¬ 
plete with insulating joints. All that remains for the wire- 
man to do is to attach and connect the lamp holders. The 
insulating joints in this case are of the same general type 
as those used for the fixtures designed for‘gas only. 

Old brass gas fixtures can very often be easily remodeled 
to form combination fixtures by attaching additional arms 
for incandescent lamps, and by providing the necessary 
channels for the wires. Such work is best done in a gas 
fitter’s or brass finisher’s work shop. 

In general, every fixture should be well tested for gas 
leaks and grounds or short circuits before.being used. 
Very often it will be found cheaper and safer to use inde¬ 
pendent electric light fixtures than to attach the incan¬ 
descent lamps to gas fixtures. This is especially true in 


32 INCANDESCENT WIRING IIAND-BOOK. 


factories and similar places. The fixtures there are often 
in a deplorable condition, and should not be used as sup¬ 
ports for incandescent lamps unless first entirely overhauled 
and put in good order. 

Chapter XIV. 

Wiring of Elevators. 

The usual method of wiring for elevators is to suspend 
one end of a two-conductor cable midway between the top 
and bottom of the elevator well, and to run the other end 
to the top of the cab, fastening each end securely. Care 
must be taken to allow the cable to swing freely, so that 
the cab will not interfere with it. Some slack must be 
left, so that when the elevator is at the top or bdttom of 
the well the cable will not be pulled tight. 

At the end of the cable which is fastened in the well a 
double-pole safety plug must be placed, so that in case of 
accident to the cable it will be cut off from the feeding cir¬ 
cuit. The other end of the cable connects with the wires 
of the fixture inside the cab. 

An extra heavily insulated flexible twin cable should be 
used. The common twin flexible cable used for porta¬ 
ble lamps and for suspending lights from ceiling cut-outs 
is not suitable for this purpose. Each strand of wire 
should be at least equal to No. 14* B. & S. gauge, and 
each strand should have thick insulation of good quality. 
Both conductors should be covered and braided with cot¬ 
ton until the cable has at least an outside diameter of 
inch. A cable manufactured in this way will be cheaper in 
the end, as it will last much longer than the common twin 
cable drawn through a soft rubber tubing, which is so 
often used. Several wire manyfacturers make a special 
electric light elevator cable similar to that described. 


WIRE GAUGES. 


Chapter XV, 

Wire Gauges. 

There is a multiplicity of wire gauges. For incandes¬ 
cent wiring, however, only three are used, viz.: The Brown 
& Sharpe or American gauge, the Birmingham gauge, and 
the Edison standard gauge. 

Wires are generally “gauged” by measuring their diame¬ 
ters. What we really want to know, however, is the sec¬ 
tional area of wires, which varies in the ratio of the square 
of the diameter. A thousandth part of an inch called a 
“mil” is usually taken as the unit of measure of the 
diameter of a wire. 



Since wires are round, and the areas of circles increase as 
the squares of the diameters, we may regard the “mil” as 
circular wire. 

By squaring the diameter in “mils” of any wire, we 
obtain at once its area in “circular mils,” that is to say, the 
number of unit wires to which it is equivalent. 

In Table I are given the circular mils for the three wire 
gauges named. In ordering special sizes of wire, it is 

( 33 ) 













34 INCANDESCENT WIRING HAND-BOON. 

always advisable to give the cross-section of the wire in 
circular mils, not the gauge. 

One mistake often made is to call, for instance, “ oooc 
wire ‘four o” wire. This is entirely wrong. 

Table I shows that in the B. & S. gauge a “oooo” wire 
is equal to 211,600 circular mils, while the term “four o” 



wire indicates a conductor made up of four single “o” wires 
equal to 105,592X4=422,368 circular mils. 

In Table II are given other valuable data covering 
electric light conductors. 

Figs. 21 and 22 show two familiar types of wire gauges. 
The micrometer gauge is preferable as it measures the 
diameter of a wire in mils, and will answer in every case, 
no matter which gauge may be used by the manufacturer. 


GENERAL ELECTRICAL DATA. 


Preliminary to the explanation of the methods employed 
in calculating sizes of wires and percentages of loss in con¬ 
ductors a few electrical data will be given which may help 
the beginner to understand the underlying principles. 

The ordinary statement that an electric current is flowing 
along a wire is only a conventional way of expressing the 
fact that the wire and the space around the wire are in a 
different state from that in which they aie when no electric 
current is said to be flowing, 

To illustrate the action of this so-called current, it is 
■generally compared with the flow of water. In comparing 
hydraulics and electricity, it must be borne in mind, how¬ 
ever, that there is really no such thing as an “electric 
fluid,” and that water in pipes has mass and weight, while 
electricity has none. Whatever electricity may be, it is 
not matter, and it is not energy. We do not speak of water 
as energy, but we mean by a water power a quantity of 
water under a head or pressure; so a quantity of electricity 
under a pressure is stored energy, and can do work. All 
our electrical machines or batteries are merely instru¬ 
ments for moving electricity from one place to another, 
or for causing electricity when accumulated in one place, 
to do work in returning to its former level distribu¬ 
tion. 

The head or pressure of a standpipe is what causes 
water to move through the pipes which offer resistance to 
the flow. We might call this head or pressure the water- 
motive force; so in electricity, the head or pressure, or as it 
is called the electromotive force, will make the electricity 
move through the wires. 


Chapter XVI. 

Coulomb. 

The unit quantity of electricity is called the coulomb. 

( 35 ) 



36 INCANDESCENT WIRING HAND-BOON. 

Chapter XVII. 

Ampere. 

A current of water is the rate of flow , or the intensity 
or the strength at which the water flows. We say, for 
instance, the water flows through a pipe at the rate of one 
gallon per second. Similarly the unit of electric current is 
one coulomb per second. This is the ampere or unit rate of 
flow, or unit of current strength, or simply the unit of cur¬ 
rent of electricity. 

In the case of the water flow, we have no single word to 
express the strength of the current, but have to speak of 
quantity and time. 


Chapter XVIII. 

Volt. 

The unit of electric pressure, or electromotive force or 
difference of potential, is called the volt. We speak of an 
electromotive force of so many volts as we might speak of 
a head of water of. so many feet, or of a steam pressure of 
so rpany pounds to the square inch. Water may fall from 
a higher to a lower level, a certain vertical distance, say of 
ten feet, so of electricity it is said to fall through a differ¬ 
ence of potential, of say ten volts. 

There is a difference in the meaning of the terms “differ¬ 
ence of potential” and “electromotive force,” although in 
most cases these two terms are equivalent. In the case of 
a water standpipe, the height or head of the fluid would be 
the “potential,” and the difference between head and lower 
level the “difference of potential,” while the tendency to 
flow produced by the potential would be the “electromo¬ 
tive force.” 

Chapter XIX. 

Ohm. 

A pipe of small diameter offers a greater resistance to 
the flow of water than a pipe of larger diameter. So a 
wire of small diameter offers more resistance to an electric 
current than a wire of large diameter. If we double the 
cross-section of a wire we halve its resistance. If we 
double the length of a wire, we double its resistance. If 
we double the cross section and double the length of a 
wire, the resistance remains the same. This law may be 
expressed thus: 


GENERAL ELECTRICAL DATA. 


37 


For a wire of a given substance the resistance is directly 
proportional to the length, and inversely proportional to 
the cross-section. The unit of electrical resistance is called 
•an ohm. 

Chapter XX. 


Conductors and Insulators. 


Bodies in which the electric current moves freely are 
called conductors, and those in which it does not move 
freely are called insulators. There is, however, no sub¬ 
stance so good a conductor as to be devoid of resistance, 
and there is no substance of so high a resistance as to be 
strictly a non-conductor. 

In the following list the substances named are placed in 
order, each conducting better- than those below it in the list: 


Best Conductor 

Silver. 

Copper. 

Gold . 

Zinc . 

Platinum. 

Iron. 

Tin. 

Lead . 

Mercury. 

Charcoal .... 

Acids. 

Water . 

The body. 

Cotton. 

Dry Wood.... 

Marble. 

Paper. 

Oils. 

Porcelain. 

Wool. 

Silk. 

Resin .... 
Gutta-Percha.. 

Shellac . 

Ebonite. 

Paraffine...... 

Glass. 

Dry Air. 

Worst Conductor.. 


f Good Conductors. 


i 


< 


>- Partial Conductors. 


Non-Conductors or Insulators. 



























38 INCANDESCENT WIRING HAND-BOON. 

Chapter XXI. 

Ohm’s Law. 

Ohm’s law expresses the relation of the three units, 
ampere, volt and ohm to each other. The law states that 
the current strength in any circuit is directly proportional 
to the electromotive force, and inversely proportional to the 
resistance. This law may be expressed in an equation, 
viz.: 

_ . Electromotive Force in Volts. 

Current in amperes— -5 — ; - ;—tvt - 

Resistance in Ohms. 

This equation is generally written in symbols thus: 

E 

C= — , 

R 

C denoting current strength; E, electiomotive force; and 
R resistance. 

This law may also be written: 

E=C X R or 
E 

R=—. 

C 

Chapter XXII. 

Conductivity. 

Conductivity is the inverse of resistance. The term 
expresses the capability of a substance to conduct the elec- 

1 

trie current. If Co is the conductivity of a substance, — 

Co 

1 

is its resistance, and if R is the resistance of a body, — is 

R 

its conductivity. Good conductors of heat are also good 
conductors of electricity. 

The figure which indicates the relation between one sub¬ 
stance and another as to their capacity to conduct electric¬ 
ity is called, “ relative conductivity.” Taking the relative 
conductivity of silver as 100, that of pure copper is 96. 
The “ specific resistance” of a substance is the reverse of 
its relative conductivity. The specific resistance of a sub¬ 
stance is generally expressed as the resistance of a centi- 




GENERAL ELECTRICAL DA TA ,. 


39 


meter cube of that substance in thousand-millionths of an 
ohm. The following table gives the data for a few metals: 

Relative 
Conductivity. 


Substance. 


Specific 

Resistance. 


Silver. 

Copper . 



Gold. 

• -- 2 .i 54 .. 


Iron (soft). 

- 9 . 8-7 . 


Lead. 

•••• 19.847 . 

... . 8 

German Silver . 



Mercury (liquid). .. ., 


- 1.6 


The specific resistance of copper is therefore: 
Touijoouooo ohms > or 1-642 microhms. * 


Chapter XXIII. 

Divided Circuits. 

If a circuit divides, as in Fig. 23, into two branches at 
A, uniting again at B, the current will also be divided, part 
flowing through one branch and part through the other. 



Fig. 23. — Divided Circuits, 

The relative strength of current in the two branches will 
be proportional to their conductivities . 

In fact, this law will hold good for any number of branch 
resistances connected between A and B. Conductivity is, 
as shown before, the reciprocal of resistance. If, for in- 

* The prefixes “ meg ” and “ micro ” denote million and millionth. 
For example, a megohm equals 1,000,000 ohms, a microhm equals 

T?T) 0 QUff of an ° hn b 




















40 INCANDESCENT WIRING HAND-BOOK . 


stance, we assume that the resistance of r=io ohms and r x 
=20 ohms, the current through r will be to the current 
through r x a$ to 2 V This may be written in the form 
of a proportion: 

T .i_2 . 1 

TO • 20 : • 25 • 25 

or as 2 : i, 

or, in other words, § of the total current will pass through 
r and ^ through r x . The joint resistance of the two 
branches between A and B will be less than the resistance 
of either branch singly, because the current has increased 
facilities for travel. In fact, the joint conductivity will be 
the sum of the two separate conductivities. Taking again 
the resistance of r= io ohms and rj=20 ohms; we have 
the joint conductivity iV 4“55 —5 S 5* and taking the recipro¬ 
cal of we get - 2 3°-=6| ohms as the joint resistance. In 
most of the cases we have to deal with, the resistances of 
the different branches will be alike; this simplifies the calcu¬ 
lations considerably Take, for instance, two branches of 
ico ohms’ resistance each and find the joint resistance. 

Demonstration: i55+T55 == T55 i the reciprocal is 
■Ml a =5o ohms, or in words, the joint resistance is one- 
half of the resistance of a single branch, and each branch, 
of course, will carry one half of the total current in am¬ 
peres. 

With three branches of equal resistance the, joint resist¬ 
ance will be with 4 branches J; with ico branches 
of the resistance of a single branch. 

If, for instance, the resistance of an incandescent lamp 
hot is 180 ohms, the joint resistance of 100 such lamps, 
connected in multiple arc, is ohms. 

If we assume the electromotive force of the system to be 
no volts we find according to Ohm’s law the current for 
100 lamps to be =61.11 amperes, or the current passing 
through each lamp would equal {£§=.61 ampere. 

Chapter XXIV. 

Work, Energy, Power. 

As a quantity of water moving from a higher to a lower 
level will do work, so also will a quantity of electricity 
falling through a difference of potential. The mechanical 
unit of work is the foot-pound. If we raise one pound one 
foot, we do one foot-pound work. It makes no difference 
whether we perform this work in one minute or in one 


GENERAL ELECTRICAL DATA . 


4i 


year; we may do our work at different speeds. So in 
electricity, one coulomb falling one volt in any length of 
time is the unit of electrical work, and is called the volt- 
coulomb or the joule. As the energy of a body is meas¬ 
ured by the work it can do and heat is only another form 
of energy, the same unit is used for work, energy and heat. 

In practice we want to know at what rate we can do 
a certain amount of work The rate of doing work is 
called power. In mechanics we use the horse power as the 
unit, which is the work done by raising 33,000 pounds one 
foot in one minute, or 550 pounds one foot in one second, 
or one pound 550 feet in one second, etc. The electrical 
unit of rate of doing work is when a coulomb of electricity 
falls through one volt in one second, or as one coulomb 
per second is one ampere, we may say the electrical unit of 
power is when electricity falls through one volt at the rate 
of one ampere. 

This unit of power is called the volt-ampere, dr the watt 
One watt equals of a horse power, or one horse power 
equals 746 watts. Hence we may express electrical work 
thus: 

watts 

Horse power= or W at d s== H. P. X746. 

As one watt is the product of bne ampere and one volt, 
it can easily be seen that we can do work at the same rate 
with great current strength and low electromotive force, or 
with small current strength and high electromotive force, 
for instance: 100 amperes X 10 volts=i,ooo watts, 10 
ampere X 100 volts=i,ooo watts. 



CALCULATING SIZES OF 
WIRES. 


Chapter XXV. 

Plans and Symbols. 

When the wire contractor has decided upon the gen¬ 
eral system to be followed in running wires and in locating 
switches and cut-outs, he should make a general plan. 
This plan should show the location of each incandescent 
outlet with the number of lamps, and give in each case the 
distance from the dynamo or main distributing point. 
The following symbols are generally used in such a plan: 



Sixteen candle power lamp without key. 



Sixteen candle power lamp with key. 


-T 


Two-atm bracket with kev-holders. 



Three-light chandelier with key-holder. 



Ten candle power lamp. 



CALCULA TING SIZES OF WIRES. 


43 


® 

Thirty-two candle power lamp. 

0 

/ 

Wall switch. 

D 

Safety plug. 



Drop of Potential and Loss of Energy. 

If a current of constant strength is passing through a 
circuit of uniform resistance, the potential will fall uni¬ 
formly. 

A B, Fig. 24, represents a wire of uniform thickness, 
marked off into 10 equal parts. If the potential or e. m. f. 




+ 


3 





Fig. 24. — Fall of Potential along a Circuit. 


between A and i? measures 100 volts, thee. m. f. measured 
at the terminals of each of the equal divisions will be 
10 volts. 






44 INCANDESCENT WIRING HAND-BOOK. 


If the circuit offers uneven resistances to the passage of 
the current the potential will fall unevenly; and it will be 
found it will fall most rapidly through that part of the cir¬ 
cuit which offers the greatest resistance. In fact the fall 
of potential in any part of a circuit is in every case propor- 
tional to the resistance of that part of the circuit. 

A C and B D , Fig. 25, are conductors of 10 ohms’ resist¬ 
ance each. C D is an incandescent filament of 180 ohms 
resistance hot.* 

The total resistance of the circuit would be io-|-i8o-(-io 
= 200 ohms, or in other words 2 1 ohms or 10 per cent is 
represented in the conductor and q per cent, in the lamp. 

Assuming the e m. f. between A and B to be 100 
volts, 10 per cent, or 10 volts will be lost in overcoming 
the resistance of the conductors and qo per cent, or 90 
volts will be expended in the lamp. The loss in the wire 
•of course is not desired but is a necessary evil, hence the 
resistance of the wire conductors might be termed the 


A 

B- 


io Ohms 


10 Ohms 


Western Electrician , Chi. 



180 Ohms 


Fig. 25. — Distribution of Resistances and 
Potentials. 


wasteful resistance, and the resistance offered by the lamp 
as the useful resistance. 

The percentage of the total potential which is wasted in 
the conductors is called the “ Drop of Potential,” or 
briefly the “drop.” 

As the loss of energy for the same current strength in 
any particular case is proportional to the “ drop” it is cor¬ 
rect to speak of the “ percentage of energy” lost in the 
conductors. In the last example we may therefore say 
* either that there is a 10 per cent, drop, or that 10 per cent, 
of the energy is lost in the conductors. 

Electrical energy, as explained in Chapter XXIV, 
may be found by multiplying the current in amperes 
by the e. m. f. in volts. According to Ohm’s law 

*Note.—I n these calculations the resistance of an incandescent 
lamp is assumed as that of the carbon filament when hot. Carbon 
filaments when cold are of much higher resistance than when hot. 





CALCULATING SIZES OF WIRES. 


45 


C =j7 or using the figures of the last example, C = |$g = 

34 ampere. If we now multiply 34 by the e. m. f. 
we get the energy in watts: 34X90=45 w'atts, the en¬ 
ergy expended in the lamp; 34X10=5 watts, the energy 
lost in the conductors. We see that 5 watts form 10 per 
cent, of the total energy of 50 watts, and that therefore 10 
per cent, of the energy is lost in the conductors. 

It may now be readily understood how the sizes of wires 
for certain percentages of loss may be determined. Let 
us take 100 lamps of 180 ohms’ resistance each. The total 
resistance of these lamps, joined in multiple, is Jjjg, or 1.8 
ohms. (Compare Chapter XXIII.) 

The problem is to lose 10 per cent, of energy in the 
conductors; in Fig. 26, 1.8 ohms represent then 90 per cent, 
of the total resistance which includes lamps and conductors. 
The total resistance of lamps -f- conductors is therefore 
_i.8X 100 

—-= 2 ohms and the resistance of the conductors 

90 

=j 2 (5 or .2 ohm. Suppose the distance from dynamo to 
lamps is 500 feet, the whole length of the circuit is 1,000 
feet. The problem is now to determine the size of a cop¬ 
per wire whose resistance for 1,000 feet of length is .2 
ohm. We may use Table II. In Column No. 11 the 
resistances of copper wire per 1,000 feet are given. The 
nearest number to .2 in that column is found to be .205, 

_ No Oh m . _ 

A 500/I. i j' 8 ohms 

»_ Soo/t- __J 

JfoOAin. Western Electrician, Chi. 

Fig. 26. — Distribution of Resistances and 
Potentials. 

which corresponds to No. 3 B- & S. wire. This is the re¬ 
quired size of the wire. 


Chapter XXVII. 

Practical Rules for Determining Proper 
Sizes of Wires. 

Although a general explanation of the principles under¬ 
lying the calculation of the sizes of wire was given in the 





46 INCANDESCENT WIRING IIAND-BOOK. 

previous chapter, it is necessary to have practical rules for 
this purpose—rules which will enable us to determine the 
size of wire without the aid of a table. 

The resistance of a unit wire, i. e., a pure copper wire 
i foot long and i circular mil in cross-section, measured at 
75 0 Fahrenheit, is 10.79 ohms. 

Suppose in Fig. 27 a represents the unit wire; b a wire 
of the same cross-section (one circular mil) but 2 feet long. 
If the resistance of a is 10.79 ohms, it is obvious that the 
resistance of b will be twice that of a. Let us assume 
farther that c is a cable 1 foot long and of two circular 
mils cross-section. Its resistance naturally will be % th at 
of a. (Compare Chapter XXIII on Divided Circuits.) 
Suppose d is a cable 2 feet long and of two circular mils 

"C - AU 


bm. 


3 



Fig. 27. — Resistances of Wires. 

cross-section, its resistance will then be equal to a. This 
demonstration leads us to the first rule: 

RULE I. The resistance of a copper wire is equal 
to its length in feet multiplied by 10.79 an d divided by 
its cross-section in circular mils. 

We may write this rule in symbols thus: 

10.79XL 

d 2 

in which R is the resistance in ohms, L the length of wire 
in feet, and d 2 the square of the diameter in mils. 

10.79XL 

We can also write the formula thus: d 2 = -j-7 - 

from which we may deduce: 

RULE II. The cross-section of a copper wire in cir¬ 
cular mils is found by multiplying 10.79 by its length 
in feet and dividing the result by its resistance in ohms. 












calculating sizes of wires . 


47 


Example.—F ind the cross-section of a wire 1,000 feet 
long and of a resistance of ioo ohms. 

10.79X iot o_ 


d 2 = 


too 


= 107.9 circular mils. 


In incandescent wiring, however, the resistance of this 
wire is a certain percentage of the total resistance of con¬ 
ductors and lamps. 

The total resistance of a certain number of lamps joined 
in multiple arc is found by: 

RULE III. The total resistance of lamps in mul¬ 
tiple arc is found by dividing the resistance of one 
lamp when hot by the number of lamps. 

We may also write this as a formula thus; 

r of lamp hot 

1 otal K= - - - r —, - • 

number ot lamps 

It may be mentioned that the resistance of a lamp when 
hot may be found by dividing the e.m.f. by the current. 
(Compare Ohm’s law.) 

Example. —Find resistance of a lamp hot of no volts 
e.m.f. and .55 amperes of current: 

11o X100 

?== - =200 ohms. 

55 


Example. —Find the total resistance of 50 no volt 
lamps connected in multiple. R=^° 0 n =4 ohms. 

It will be remembered that the joint resistance of the 
lamps is only a part of the total resistance of the circuit, 
which includes wires and lamps. (See Fig. 26 ) 


RULE IV. The resistance of the conductor is 
found by multiplying the total resistance of the lamps 
by the percentage to be lost, and by dividing the 
product by 100 minus the percentage of loss. 


Written as a formula, this rule becomes; 

rX% 


R= 


100- 


If we combine Rules III and IV we obtain: 
r hot w % 


R= 


N 


X- 


100 —% 


, or in words: 


RULE V. The resistance of the conductor is found 
by dividing the resistance of one lamp hot by the num¬ 
ber of lamps (N) joined in multiple arc, and multiply¬ 
ing the quotient by the percentage of loss, divided by 
100, minus the percentage. 








4 S INCANDESCENT WIRING IIAND-BOOII. 


Example —Find the resistance of a conductor for 50 

lamps, each of 200 ohms’ resistance hot, with \o% loss. 

20 10 10 40 4 

R= — X - =4 X — = =- or .44 ohm. 

50 100—10 ^ 90 90 9 ^ 

It is not sufficient, however, to find the resistance of the 

copper conductor. It is also necessary to determine its 

cross-section in circular mils. 

10.79XL. 

It is stated under Rule I that d 2 = - ^- The ex¬ 

planation of the symbols is repeated: 10.79 ohms repre¬ 
sent the resistance of a unit wire, L is the length of a 
circuit which is twice the distance, R is the resistance of 
conductors. 

If for L in the formula we substitute twice the distance, 
10.79X2D 

2 D, we have d 2 = - jy- and if we now insert for R 

the value as given in Rule V and multiply 2 by 10.79 we 
find that 

ax.SSXO 


r hot 


N 


-x 


(100—5 


We can simplify this and obtain the general important 
wiring rule: 


RULE VI.d 2 = 


2i.58xDxN >< .(ioo— D. 


in which d 2 = 


r hot % 

circular mils: D=distance in feet; the distance is \ the 
full length of the circuit; N=number of lamps; r=re- 
sistince of one lamp hot; $=desired percentage of 
loss in conductor given as a whole number and not as 
decimal fraction. 

Example. — 150 lamps are to be run 4 co feet with 5 per 
cent. loss. The voltage of the lamp is no volts, and the 
current per lamp is | ampere. 

Demonstration'. We must first find the resistance hot of 

, . , volts no 

one lamp: resistance hot= _ — = 220 ohms. 


amperes yz 
Working by Rule VI we obtain: 

_2 1.58X 400 X150 (100—5) 

2-0 * 5 

, 21.58X400X150 95 

d 2 =--Xy =111,823 circular mils. 


220 















CALCULA TING SIZES OF WIRES. 


40 


Bv referring to Table I we find that this wire is a little 
larger than No. o B. & S. gauge. 

Rule VI will hold good for all lamps and for every 
percentage of loss. The cross-section of the wire is 
found in circular mils, and no table is necessary. 

RULE VII. Where lamps or groups of lamps are 
placed at different distances from the dynamo, deter¬ 
mine first the proper wire for each lamp or group of 
lamps if placed on independent circuits starting from 
the dynamo, then combine all wires running in the 
same direction.* 

Fig. 28 shows three groups, 1, 2 and 3, of 50 lamps 
each. D is the dynamo, and -f- and — its positive and 
negative binding posts. The first group is 100 feet from 
the dynamo, the second 250 feet, and the third group 350 
feet. We figure on lamps of 220 ohms resistance hot and 
5 per cent. loss. Take the most distant group first. 
Proceeding by Rule VI we find 

21.58XDXN 100—5 

d 2 = - X- 

220 ^5 

As we desire to figure on the same kind of lamps and 
same percentage of loss we may simplify our calculations by 
first figuring out the constant part of our formula or “ a 
constant” and subsequently multiplying D X N X con¬ 
stant. 

21.58. . 100—5 

K (constant)=-^-X —-— =1.86 

d 2 =DXNXi.86. d 2 ==35oX 50X1.86=32,550circular mils 
for Group 3. Taking Group 2 we find: 
d 2 =25oX50X 1.86=23,250, circular mils. 

Adding to this total 32,550 we have a wire of 55,800 
circular mils to be used for Section 2. 

Proceeding in the same way with Group 1 we find: 
d 2 =iooX5oX 1.86 = 9,300 circular mils, which added to 
the total in the last case gives 65,100 circular mils, 

From these data we conclude that we must use a wire of 
65,100 circular mils between the dynamo and Group i;a 

*By groups of lamps is meant a number of lamps comparatively near 
each other, as for instance, lamps in a room of a building or on a 
chandelier, or, in station lighting the lamps in one store. Up to the 
first group, the mains must be of sufficient size to carry all the lamps 
or groups of lamps in circuit. Beyond the first lamp or group the 
mains may diminish as the number of lamps or groups dimmish. 






SO Lamps JO Lamps joLamps 

loofeet 2 jo feet 3Jofeet 


50 INCANDESCENT WIRING IIAND-BOOK. 





o 

DS 

O 

o4 

O 

C/5 

W 

04 


O 

g 

,J 

D 

U 

< 

u 


o 

£ 



wire of 55,800 circular 
mils between Group 1 
and Group 2, and a wire 
of 32,550 circular mils 
between Group 2 and 
Group 3. 

RULE VIII —First 
calculate the sizes of 
mains and feeders; 
then determine the 
sizes of branches. Not 
more than 5 per cent, 
loss must be allowed 
between the main dis¬ 
tributing point and 
lamp outlets. 

In the closet system, 
for instance, 3 per cent, 
loss may be allowed from 
the dynamo or main dis¬ 
tributing point to the 
closets and 2 per cent, 
from the closets to the 
lamp outlets. 

The percentage of loss 
in the wires should be 
made as small as possible, 
for two reasons: In the 
first place, a large drop in 
the wires involves con¬ 
siderable waste of energy, 
and secondly the system 
will not admit of auto¬ 
matic regulation of the 
pressure. Complaints are 
often made that an in¬ 
candescent dynamo does 
not regulate very closely, 
i. e., when a number of 
lamps are thrown on or 
off, the remainder of 
the lamps become dim¬ 
mer or brighter as the 
case may be. It is ob- 













CALCULATING SIZES OF WLRES. 


5i 


vious that, no matter how efficient the dynamo or the trans¬ 
former may be, a considerable loss in the wires will inter¬ 
fere with the maintenance of even pressure throughout an 
entire system. 

Suppose we have figured mains for 100 lights on a basis 
of 20 per cent, loss; lamps to be of the 112 volt class. In 
this case the dynamo must run at 140 volts, with 100 lamps 
in the circuit; 

20 per cent, of 140—28 volts, which is the drop in the 
wires. If 50 lamps are switched out, and the potential of 
140 volts at the dynamo remains unchanged, the voltage 
at the lamps will increase 50 per cent, of 28 volts, or to 
112-(— 14 = 126 volts. 

This condition of course would be fatal to the life of the 
lamps. Again it may happen that while on one branch all 
the lamps are running, on another, only a small fraction of 
the total number of lamps is switched on. The lamps on 



Fig. 29. — Loop Circuit for Equal Potentials. 

one circuit would thus burn at nominal pressure or candle 
power, while on another circuit they would be far above 
the nominal candle power. If only a small percentage of 
loss has been allowed in the wires, this condition cannot 
ensue, as the maximum difference in the potentials of the 
different circuits must necessarily be within the percentage 
of loss allowed in the wires. 

The foregoing considerations lead us to: 

RULE IX.—Calculations should be so made that 
substantially the same potential (within two or three 
volts), may be maintained at every point in the cir¬ 
cuit, no matter how many or how few lamps be burn¬ 
ing at different points. 

It can easily be seen that that would be an ideal 
system, where each lamp was provided with a separate 
circuit direct to the dynamo. No matter how many lamps 
were switched on or off, the percentage of loss in the 








52 INCANDESCENT WIRING HAND BOOK. 


other circuits would not be altered. Of course such a 
system is impracticable. The next best thing is the sub¬ 
division of the system of wiring into as many independent 
circuits as possible. The adoption of this plan will result 



in many advantages, for example, faults in the insulation 
will be more readily located and the use of large fusible safe¬ 
ty plugs, which act very sluggishly when of large cross-sec¬ 



tion, will be avoided. Fifty lamps should be the maximum 
number on a single circuit within a building. 

Many plans have been proposed for the maintenance of 
an even potential, but the best made is to keep the percent- 












CALCULA TING SIZES OF WIRES. 


53 


age of loss in the wires very low. The only objection to 
the plan is that it involves additional cost for large copper 
wires. This expense, however, is small in the wiring of a 
building in comparison with labor and other items of 
expense. There is another reason why the loss within a 
building should be kept very small, which will be taken up 
in the chapter treating of “Safe Carrying Capacity ” 

Fig. 29 represents a plan on which equal potentials must 
necessarily be obtained at all lamps. 

Fig. 30 represents the so-called closed loop plan, with 
feeders diametrically opposite each other. 

It might be stated that as ageneral rule in order to secure 
an equal potential, it is advisable to cross-connect the mains 
whenever possible, and attach separate feeders at the 
centers of distribution. 

Fig. 31 shows the proper location of feeders. 

Chapter XXVIII. 

Safe Carrying Capacity. 

The National Board of Fire Underwriters specifies that 
the carrying capacity of a conductor is safe when the wire 
will conduct a certain current withoui becoming painfully 
warm when grasped by the closed hand. 

All wires will heat when a current of electricity passes 
through them. The loss of energy which was referred to 
in the previous chapter is a loss only in the sense that it is 
lost for useful work. 

Nothing is lost in nature; electrical energy may be trans¬ 
formed into heat, light, motion, etc., but energy cannot be 
lost. This so-called lost energy in the wires will there¬ 
fore re-appear as heat, although not wanted in the wire. 

The greater the current in amperes and the smaller the 
wire, the greater the heating effect. 

Larger wires will be heated comparatively more than 
smaller wires as the latter have comparatively more radi 
ating surface. 

It is approximately true that the heat increases directly as 
the square of the current, and inversely as the cube of the 
diameter of the wire. This statement may be written thus: 
c 2 

Heating effect^—where c is the current and d the 
diameter of the wire. . 


54 INCANDESCENT WIRING HAND-BOON. 

In Table I are given the carrying capacities in am¬ 
peres, and lamps of different sizes of wire. A wire is here 
assumed to have a safe carrying capacity when its temper¬ 
ature, is not increased over 30° F. above that of the 
surrounding air, when conducting current. In many tables 
a much higher temperature is adopted as a standard. It 
is safe to fix upon 30^ F. as a maximum, however, as many 
circumstances, such as may be found in hot engine rooms, 
proximity to steam pipes, in twists or sharp bends in the 
wire, may cause a considerably higher rise of temperature 
than anticipated. The following empirical formula is used 
for calculating the carrying capacity: 



where c stands for current, d for diameter jn mils, and 
2,500 is a constant. 

RULE X. Ascertain the proper size of wire ac¬ 
cording to Chapter XXVI for permissible loss, 
number of lamps and distance. Then determine by 
Table I whether the wire has the necessary carry¬ 
ing capacity. If not, assume smaller percentages of 
loss, until a wire is found that will be large enough to 
carry the current safely. 

It may tend to make certain phenomena more easily 
understood to state that the electric current passing through 
a wire is frequently compared to water flowing through a 
pipe. Prof. Ayrton says in “Practical Electricity.” this 
analogy, however, like many other analogies, must not be 
strained too much; for example a bend in the pipe, even 
with a steady flow of water, is found to cause a falling off 
in the water pressure; whereas, a bend in a wire has no 
effect on the electric potential if a steady current is flowing; 
or, again, if there be a sudden expansion or contraction in 
a pipe, there is a sudden alteration of the water pressure, 
which has no analogy in any sudden alteration of the elec¬ 
trical potential at a point in a circuit where the sectional 
area of the conductor changes abruptly. In fact, the flow 
of water or of gas in a pipe can be diminished to any 
extent by a contraction of one point only , which may be 
practically effected by partially closing a tap or cock; 
whereas, if an electric circuit consist of many yards of wire, 
no appreciable alteration of the current will be produced 
by 4 making only half an inch of the wire, say one-tenth of 


CALCULA TING SIZES OF WIRES. 


55 


its previous sectional area. The carrying capacity of any 
part of a wire, however, is materially reduced by making it 
of a smaller cross-section, and such a reduction in sectional 
area may cause a considerable heating of that portion of 
the wire. 

A sharp bend in a wire is therefore only dangerous as 
it reduces the sectional area, and not because it introduces 
a resistance. 

Fig- 3 2 explains how a sharp bend may cause a wire to 
be partially torn asunder, and thus decrease the sectional 
area and cause undue heating at this point. 

It may be stated as a general rule, that when a large 
percentage of loss is allowed with lamps at short distances, 
the size of wire calculated simply in accordance with 



Fig. 32.— Sharp Bend in a Wire. 


resistance rules will be found too small to carry the cur¬ 
rent safely. 

This simple fact is often overlooked, and even though 
wires may have been correctly calculated for a uniform 
percentage of loss, they will become painfully hot simply 
because the table of carrying capacity was not consulted. 

The cross-connection of mains wherever possible, as 
recommended in the previous chapter, for the purpose of 
maintaining equal potentials, will also often reduce the 
heating effects of the current. A case came under the 
author’s observation which will well illustrate this fact. 
A circle of about 50 lights was wired, Fig- 33- After the 
current had been turned on the wires of the circle became 
hot, and there was quite a perceptible difference of candle 




56 INCANDESCENT WIRING HAND-BOOK. 


power between the lights near A and those near B. In¬ 
vestigation disclosed the fact that the loop, contrary to 
instructions, had been left open. A few inches of wire 
connecting A and B and C and D remedied the fault; the 



wires remained cool and the candle power was practically 
the same all around the circle. 

The smallest wire used for incandescent wiring should 
be at least of 250 circular mils cross-section. Smaller 
wire will break too easily when handled, and thus cause 
endless trouble. 


Chapter XXIX. 

The Three-Wire System. 

Chapters XXVI and XXVIII which treat of “Drop of 
Potential” and “Safe Carrying Capacity” have reference 
only to conditions met with in a multiple arc system of 
distribution. 

It was explained briefly in Chapter II that in the three- 
wire system the electromotive force is double and -the cur¬ 
rent is one-half that required for the same number of 
lamps on the multiple arc system. 

All the rules given in the previous chapters may readily 
be applied to the three wire-system. 

Let us again compare these two systems. 

Example: Find the electrical data for four lamps of 
100 volts and 200 ohms’ resistance each for both systems. 





CALCULA TING SIZES OF WIRES. 


57 


Demonstration : The current for one lamp according to 
Ohm’s law=!§§ = ! ampere 


:: o ooo 

CN\\ 


Fig. 34. — Multiple Arc System. 

a. Multiple Arc System. (Fig. 34.) Joint resistance=- 2 -£-° 
= 50 ohms; total electromotive force =100 volts; total cur¬ 
rent = 

t w electromotive force 

|X 4-2 amperes or - resistance -W-* amperes. 

b. Three-Wire System. (Fig. 35.) The joint resistance 
may easily be found by omitting from the calculation the 




third or neutral wire. We will then have two series of 
two lamps each. The resistance of two lamps joined in 
series will be of course twice that of one lamp, or 400 
ohms. 

The joint resistance of two series will therefore be - 4 -| a 
=200 ohm^. (Compare Fig. 2, Chap. II), or in other 
words the joint resistance of the lamps in the three-wire 
system will be four times the joint resistance of the same 
number of lamps in multiple arc. 















58 INCANDESCENT WIRING HAND-BOON. 


The total electromotive force in the three-wire system of 
course will be twice that of the electromotive force in the 
multiple arc system. 

total electromotive force 

Again, the total current will equal total resistance 

or, C=|oo=i ampere, or in other words, the total current 
required for the lamps in the three-wire system, will be 
^ of the total current required for the same number of 
lamps in the multiple arc system. 

With this demonstration in mind we are ready to form 

RULE XI. For the same kind and same number 
of lamps the joint resistance of the lamps in the three- 
wire system is four times that of the multiple system; 
the total electromotive force of the lamps in the 
three-wire system is twice that of the multiple arc 
system, and the total current strength of the lamps 
in the three-wire system is one-half the correspond¬ 
ing unit in the multiple arc system. 

It can easily be seen that as the joint resistance of the 
lamps is four times greater in the three-wire system than 
in the multiple arc system, the resistance of the positive 
and negative conductors will be four times greater for the 
same percentage of loss. In other words, the cross-section 
of the wires in the three-wire system is % that of the wires 
in the multiple arc system for the same percentage of loss. 
This gives us: 

RULE. XII. In order to find the proper size of 
wire for the three-wire system, first find the size of 
wire for the same number and kind of lamps on the 
multiple system in accordance with Rules VI and 
VII, then divide the number of circular mils by four. 

The sum of the lengths of the positive and negative 
wires is the entire length of the circuit in the three-wire 
system, and the amount of copper required for the circuit 
is equal to one-fourth the amount of copper required in a 
multiple arc circuit; the length of the center or neutral 
wire, if of the same size as the positive and negative leads 
will be only one-half the length of the total circuit; hence 
the total amount of copper in the three-wire system will be 
X ~b % — % °f the amount necessary in the case of the 
multiple system. 

As a matter of fact the neutral wire may be made smaller 
than the positive and negative wires, as it seldom will be 
called upon to carry more than a fraction of the maximum 




CALCVLA TING SIZES OF WIRES. 


59 


current. For practical reasons, however, it is advisable to 
make all three wires of the same size. 

It will be seen that as the number of circular mils per 
wire in the three-wire system is % the cross-section per 
wire in the multiple system, the carrying capacity in 
amperes of course is also reduced to 

When Table I for the three-wire system is used it 
should be borne in mind that only tzvice the number of 
lamps may be carried by the wires, as the current is reduced 
to 3^ f° r th e same number of lamps. 

The three-wire system in a building is generally followed 
throughout the whole network of feeders, mains, branches 
and sub-branches, down to circuits of from three to six 
lights; smaller numbers would then be connected in simple 
multiple arc. 

Chapter XXX. 

Explanation of Tables. 

Wiring Tables 3, 4 and 5 may be used by any one 
who does not care to study the principles underlying the 
calculations of the sizes of wires as explained in Chapters 
XXVI and XXVII; but even to those who thoroughly 
understand the demonstrations, the tables will be found of 
great convenience. 

The first thing to do is to select the table for the lamps 
which are to be used. Let us consult the table for data 
relating to the 1 o volt’lamps. 

We find in the horizontal columns at the top and bottom, 
numbers which correspond to “lamp-feet.” (Lamp feet is 
a brief expression used to denote the product obtained by 
multiplying the number of lamps by the distance in feet.) 
At the left of the table we find three vertical columns filled 
with figures representing circular mils; and also under¬ 
lined figures giving the numbers of the Brown & Sharpe 
gauge. Each horizontal column corresponds to a vertical 
column. 

The radial lines starting near the left hand corner rep¬ 
resent percentages of loss. Each small space in the 
inside columns represents 20^0, in the middle columns, 
500 and in the outside columns, 125; that is to say in the 
horizontal columns the numbers represent lamp-feet; in the 
vertical columns the numbers represent circular mils, 
except where underscoied, when they represent the number 
of the wire according to Brown & Sharpe gauge. 


6o INCANDESCENT WIRING IIAND-BOOK. 


Although the difference would be very slight in any case, 
it is necessary to note, for those who may desire absolute 
accuracy in determining the circular mils, that the short 
heavy lines beneath the Brown & Sharpe gauge figures in the 
vertical column, are the correct gauge lines and may be 
understood as extending the full width of the table. 

The figures given in the columns represent thousands. 
For instance, ioc denotes 100,000; 4.25 =4250; 2.5=2500, 
etc. 

Example: Find the size of wire for 100 iio volt 
lamps at 1060 feet distance, at 10 per cent. loss. 

Demonstration: 100 X 1 00 = ioo,oco lamp-feet. We 
find 100 in the inside horizontal column; we follow the ver¬ 
tical 100 line until it intersects the 10 percent, line. We take 
a ruler and lay it horizontally through this point and find it 
strikes about 88 in the inside vertical column. The proper 
size of wire has a sectional area of 88.0 >0 circular mils. 
If we wish to wire on 5 per cent, loss we follow the verti¬ 
cal 100 line until it intersects with the 5 per cent, line and 
obtain by laying a horizontal line through this point about 
186, 00 circular mils. 

From this demonstration we deduct the following gen¬ 
eral rule for computing from wire tables: 

RULE XIII.—Find the number of lamp-feet (lamp 
X feet), in one of the horizontal columns, follow the 
vertical line until it intersects the desired percentage 
line. A horizontal line laid through this point will 
show in the corresponding vertical column the cross- 
section of the wire in circular mils. 

In consulting the table, always use corresponding 
columns, If the lamp-feet are found in the middle 
column, the circular mils must be read from the middle 
column ; if the lamp-feet are found in the outside 
column, the circular mils must be read from the 
outside column, etc. 

Example: Find the size of wire for 20 no volt lamps, 
at 900 feet distance i t 5 per cent. loss. 

Demonstration'. 20 X 900=18,000. We find 18 in the 
middle horizontal column; we follow the vertical :8 line 
until it intersects with the 5 per cent, line, and following 
the horizontal line we find in the middle column 33,500 
circular mils. 

Exampie: Find the size of wire for 50 110 volt lamps 
at ico feet distance at 5 per cent. loss. 


CALCULATING SIZES OF WIRES. 


61 


Demonstration : 50 X 100=5,000 lamp-feet. We find 
5 in the middle lower column, and a glance shows us that 
the wire is over 9,300 circular mils or a little larger than 
No. 11 B. & S. gauge. We can find the same result by 
taking 5,000 in the outside horizontal column. 

RULE XIV.—The number of lamp-feet within 
moderate numbers can always be found in one of the 
three horizontal columns. Select the one which will 
intersect with the desired percentage line farthest 
from the left lower corner. If the number of lamp- 
feet is too great, and cannot be found in the table, 
divide it by 10 and find the circular mils for ^ the 
number of lamp-feet first, and then multiply the result 
by 10. 

Example: Find the size of wire for 1,000 no volt 
lamps, 1,000 feet distance at 10 per cent loss, 

Demonstiation : 1,000 X i,oco = 1,000,000 lamp-feet. 

Divide by 10 = 100,000 lamp-feet. Size of wire for 100,- 
000 lamp-feet = 88,000 circular mils, for 10 X 100,000 = 
1,000,000 lamp-feet = 10 X 88,oco= 880,000 circular mils. 

T.he 55 and 75 volt tables, of course, are to be used in the 
same manner as explained in the case of the no volt table. 

It will be noticed that the small spaces in the three 
vertical columns of all three tables represent the same 
values while the values in the horizontal columns of the 
three tables differ as follows: 


Number of Lamp-feet per 
Small Space. 


Tables. 

- 


55 Volt. 

75 Volt. 

110 Volt. 

kiside Horizontal Column. .. 

500 

1000 

2000 

Middle Horizontal Column. . 

125 

250 

500 

Outside Horizontal Column. . 

3 r • 2 5 

62.5 

125 


The tables are very simple, and will become familiar to 
the user after a short practical experience. 

The 55 volt table may be used for lamps of a voltage be¬ 
tween 50 and 60 volts, the 75 volt table for lamps of a volt¬ 
age between 70 and 80 volts, and the no volt table for 
lamps of a voltage between 100 and 115 volts. The re¬ 
sults will be accurate enough for all practical purposes. 

In calculating the tables, lamps requiring 55 watts were 
assumed. The following table gives the electrical data of 
such lamps: 









62 INCANDESCENT WIRING HAND-BOON. 


16 CANDLE-POWER LAMP REQUIRING 55 WATTS. 


Electromotive Force 

Current 

Resistance hot 

in Volts. 

in Amperes. 

in Ohms. 

no 

•50 

220 

75 

.7338 

102.207 

55 

1.00 

55 


Under Rule VII, page 49, it was shown that Rule VI 
could be simplified by calculating the constants for each 
kind of lamp and each percentage of loss. In the follow¬ 
ing table are given the constants for 55 watt lamps at dif¬ 
ferent percentages of loss in the conductors. 


TABLE OF CONSTANTS. 



H 

2% 

3% 

n 

1 5 % 


7% 



IO 36 

121% 

15% 

55 Volt 

Lamp. 

38.8 

19.2 

12.7 

9.4 

7.5 

6.1 

5.2 

4.5 

4.0 

3.6 

2.7 

2 2 

75 Volt 













Lamp. 

20.9 

10.3 

6.8 

51 

4.0 

3.3 

2.8 

2.4 

2.1 

1.9 

1.5 

1.2 

110 Volt 













Lamp. 

9.7! 

4.8 

3.2 

2.4 

1 86 

1.5 

1.3 

1 1 

.99 

.88 

.61 

.56 


The wiring formula, Rule VI, can now be written 
d 2 =NXDxK, or, the size of wire in circular mils=lamp- 
feet multiplied by constant. The constant Iv is found 
from the formula: 

21.58 100 —% 

K=-X-- 

r hot % , 

From the foregoing it will be very easy to find the con¬ 
stant for any lamp and any percentage of loss, and calcu¬ 
late the size of wire without the aid of any tables whatever. 


































CALCULA TING SIZES OF WIRES. 63 


GAUGES IN CIRCULAR MILS AND SAFE CAR¬ 
RYING CAPACITY. 

Table No. I. 


Safe Carrying Capacity. 


B.&S. 


B.W.G 


E. S.G. 


Wire heated to 30 deg. F. above 
temperature of surrounding air. 


s 

V 




^ & 

O P 

' 

(/} 

« l~ 

T3 

a 

u 

a . 

s 

03 


° c/> 

(/) 

OJ Pm 
° 6 

a 

'P s 

p 

u 

u 

u 

.c 4) 

g O 

o 

Birmingh 

Wire 

Gauge 

Edison 

Standari 

Gauge 

Number 

Ampere 

Number 
i Volt Lai 
16 c. p. 

Number 
Volt La 
16 c. p. 

Number ( 
0 Volt La 

16 c. p. 


CO 



in 

in 

lO 

c- 

£ 

220,000 



2’0 

203 

203 

278 

406 

211,600 

0000 



197.3 

197 

270 

395 

206,116 


0000 


193.5 

193 

264 

387 

200,000 



200 

189.15 

189 

259 

378 

190,000 



190 

183 

182 

249 

364 

180,625 


000 


179.3 

179 

245 

359 

180,000 



180 

174.8 

175 

240 

330 

170,000 



170 

167.4 

167 

229 

335 

167,805 

000 



165.8 

166 

227 

332 

160,000 



160 

160 

169 

219 

320 

150,000 



150 

152.5 

152 

208 

305 

144,400 


00 


148.2 

148 

203 

296 

140,000 



140 

144.8 

145 

199 

290 

133,079 

00 



139.4 

139 

190 

279 

180,000 



130 

136.9 

137 

188 

274 

120,000 



120 

129 

129 

177 

258 

115,600 


0 


125.4 

125 

171 

351 

110,000 



110 

120.8 

121 

166 

242 

105,592 

0 



117.2 

117 

160 

234 

100.000 



100 

112.5 

112 

153 

225 

95,000 



95 

108.2 

108 

148 

216 

90,000 


1 

90 

103.9 

104 

142 

208 

85,000 



85 

99.5 

99 

136 

199 

83,694 

1 



93.4 

98 

134 

197 

80,656 


2 


95.7 

96 

131 

191 

80,000 



80 

95.1 

95 

130 

190 

75,000 



75 

90.6 

91 

125 

181 

70,000 



70 

86 

86 

118 

172 

67,081 


3 


84 

84 

* 115 

168 

66,373 

2 



83.1 

83 

114 

166 
































































64 INCANDESCENT WIRING HAND-BOOK. 


GAUGES IN CIRCULAR MILS AND SAFE CAR¬ 
RYING CAPACITY. 

Table No i. 


I d’ 1 

Circular Mils. 

1 

B.& S 

V 

O4 

9M 

C3 . 

1 <s 

0 

CG 



Safe Carrying Capacity. 

Birmingham ^ 

Wire 

Gauge. q 

Edison ^ 

Standard & 

Gauge. Q 

Wire heated to 30 deg. P. above 
temperature of surrounding air. 

Number of 
Amperes. 

j Number of 

55 Volt Lamps. 
16 c. p. 

Number of 

75 Volt Lamps. 

16 c. p. 

Number of 

110 Volt Lamps 

16 c. p. 

65,000 



65 

81.4 

81 

Ill 

163 

60,000 



60 

78.4 

78 

107 

157 

56,644 


4 


73.4 

73 

100 

147 

55,000 



55 

71.8 

72 

99 

144 

52,634 

3 



69.5 

69 

94 

139 

50,000 



50 

66.8 

67 

92 

134 

48,400 


5 


65.2 

65 

89 

131 

45,000 



45 

61.7 

62 

85 

123 

41,742 

4 



58.4 

58 

79 

117 

41,209 


6 


57.8 

58 

.79 

116 

40,000 



40 

56.5 

56 

77 

113 

35,000 



35 

51.1 

51 

70 

102 

33,102 

5 



49.1 

49 

67 

98 

32,400 




48.3 

48 

66 

97 

30,000 



30 

46.6 

46 

63 

93 

27,225 


8 


42 4 

42 

57 

85 

26,250 

6 



41.2 

41 

56 

82 

25,000 



25 

39.7 

40 

55 

79 

21 904 


9 


36 

36 

49 

72 

20,816 

7 



34.6 

34 

47 

69 

20,000 



20 

83.6 

33 

45 

67 

17,956 


10 


31 

31 

42 

62 

16,509 

8 



29.1 

29 

40 

58 

15,000 



15 

27.1 

27 

37 

54 

14,400 


11 


26 3 

26 

36 

52 

13,094 

9 



24.4 

24 

33 

49 

12,000 



12 

22.9 

23 

31 

45 

11,881 


12 


22.7 

23 

31 

46 

10,381 

10 



20.5 

20 

27 

41 

9,025 


* 13 


18.5 

18 

25 

37 























































CALCULA TING SIZES OF WIRES. 65 


GAUGES IN CIRCULAR MILS AND SAFE CAR¬ 
RYING CAPACITY. 

Table No. i. 


(12 

Circular Mils. 

1 

B.& S 

V 

a* 

u 

C3 . 
X 0 

° 0 

O 

u 

CC 

B.W.G. 

E 

d 

-C a. 0J 

be 

C'~ 3 
tj> d 

E-"0 

u 

s 

Edison ^ 

Standard Y 

Gauge. p 

Safe Carrying Capacity. 

Wire heated to 30 deg. F. above 
temperature of surrounding air. 

Number of 
Amperes. 

C/5 

° G . 
b * o« 

^ 7: ^0 

~ C T—t 

z> 

10 

iO 

Number of 

75 Volt Lamps. 

16 c. p. 

Number of 

110 Volt Lamps 

16 c. p. 

8,234 

11 



17.3 

17 

23 

34 

8,000 



8 

16.9 

17 

23 

34 

6,889 


14 


15.1 

15 

20 

83 

6,530 

12 



14.5 

14 

19 

29 

5,184 


15 


12.2 

12 

16 

24 

5,178 

13 



12.2 

12 

16 

24 

5,000 



5 

11.9 

12 

16 

24 

4 225 


16 


10.5 

10 

14 

21 

4,107 

14 



10.2 

10 

14 

20 

3,364 


17 


8.8 

9 

12 

17 

3,257 

15 



8.6 

9 

12 

17 

3,000 



3 

8.1 

8 

11 

16 

2,583 

16 



7.2 

rr 

t 

10 

14 

2,401 


18 


6.8 

7 

10 

14 


1. In this table it is estimated that 1 55 volt, 16 candle power 
lamp requires about 1 ampere of current; 1 75-volt, 16 candle 
power lamp requires about .73 ampere of current; 1 no-volt, 16 
candle power lamp requires about .5 ampere of current. 

2. Lamps supposed to be in multiple arc. On the three-wire 
system the same current in amperes will suffice for a series of two 
lamps. Hence twice the number of lamps as given in the above 
table can be safely carried on the same size wires. 


















































ELECTRIC LIGHT CONDUCTORS 


XIII. 

u 

o> 

ft . 
o 6 ^ 

° CZjft 
® ^ G 

Ohms per 

Pound 

(naked) 

OO 

02N7JOOH02 

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xii. j 

hIhU 

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per 

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19605.69 

15547.87 

12330.36 

9783.63 

7754.66 

6149.78 

4876.73 

3867.62 

3067.06 

2432.22 

1928.75 

1529.69 

1213.22 

961.91 

762.93 

605.03 

479.80 

380.51 

301.75 

239.32 

189.78 

150.50 

116.05 

94 65 

ft 

X 

c3 

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£ 

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per 

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per 

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VII. 

Weight. 

© 

<D 

Pounds 

per 

1000 ft. 

co rH 02 00 CO 0^ rH 0^ o 00 CO l> CO CO AO rH Tf rH 02 rH 00 02 

CO O O O 00 *0 O rH o CO 02 oo AO JO 00CO rT GO CO rn 02 1> o 

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cS 

£ 

Grains 

per 

Foot. 

CO 0? 00 CO 02 © AO ©© t - GO rt< l> AO rH 0* CO CO COO* AO 02 rH 
CO©COC^rHL-0*JLrH(H$C^rH02AOrH f --«iOGOaOCOCOCO , '3<CO 
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TFCOCrO*rHrHrH 

> 

Sec¬ 

tional 

Area. 

Square 

milli¬ 

metres. 

OcOco 

02 GO rH02 O rH CO rH GO CO AO O C<J 02 CO rH O 02 GO CO rr {> 

rH CO O O CO t> AO O O Tf CO CO 50 i>Of-H GO aOO CO C<i co rH 
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ft kO ft CO cl CO CO rH co CO O GO CO AO ft CO 0* 0* rn rH rn 

OGOCOAOrrCOOQOJrHrMi-H 

rH 

IV. 

Square 

of 

Diam. 

Circular 

Mils. 

211600.0 

167805.0 

133079.4 

105592.5 
83694.2 
66373.0 
52634.0 
41742.0 
33102.0 
26250.5 
20816.0 
16509.0 
13094.0 
10381.0 

8234.0 

6529.9 

5178.4 

4106.8 

3256.7 

2582.9 

2048.2 

1624.3 

1252.4 

1021 5 


*H 

d> 

OP 

a 

c3 


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Published Weekly at 6 Lakeside Build¬ 
ing, Chicago. 


The ONLY ELECTRICAL JOURNAL i; the WEST. 

36 Beautifully Illustrated Pages. 

$3.00 Per Year. 

$1.50 for Six Months. 


THE BRIGHEST, 

THE HANDSOMEST, 

THE BEST 


Electrical Journal Published. 


Its Descriptive Articles and Illustrations cover 
the new Electrical Inventions of America and 
Europe. It is replete with the electrical news of 
the day. No intelligent reader who desires to 
keep up with the advance of the great Science 
of Electricity can afford to be without it. 


SAMPLE COPY, 10 CENTS. 

























Weslerr) Electric Compagy, 

CHICAGO, LONDON, 

NEW YORK, ANTWERP, 

MANUFACTURERS OF AND DEALERS IN 

ELECTRICAL 

APPARATUS 

And Sullies of Every Description, 


Contractors for installations of complete Arc and In¬ 
candescent Electric Lighting Plants, and for wiring for 
any electric lighting system. 


WE ARE THE SOLE AGENTS FOR 

DAY’S 


Kerite Insulated Wire, 

The acknowledged Standard for Durable 
and High Insulation. 

Its Merits Proved by a Record of over a Quarter ol a Centnry. 


Adapted Specially to Incandescent Electric Light 
Wiring. 




Dynamo Tenders 1 

rand-book, 

BY 

E3. BADT. 

First Edition of Twenty-Five Hundred Copies exhausted. 
Second Thousand of Second Edition now ready, 
making 4,-500 books printed to date, contain¬ 
ing additional pages, and Moonlight 
Schedule for 1SS9. 


100 Pages, 70 Illustrations, Flexible Cloth Binding, 
Size of Type Page 6x3 inches. 


Designed for Dynamo Tenders and Linemen, Stationary 
and Marine Engineers. Just the book for men who wish 
to learn how to operate and care for electric light installa¬ 
tions. The only book of the kind in the English Language. 


Price, Postage Prepaid to any address in the United States 
or Canada, $1,00. 

ADDRESS 

ELECTRICIAN pUBLI^HipIlJ dOMpAHY, 

6 Lakeside Building, Chicago, 







BELL HANGERS' 

HAND-BOOK, 

By F. B. BADT. 

106 Pages, 97 Illustrations, Flexible Cloth Binding, Type 
Page, 6x3 Inches. 

PRICE S1.00. 

jysT The bo©k 

For those engaged in Selling, Installing, or 
Handling Electric Batteries, Electric Bells, 
Elevator^ House or Hotel Annunciators, 
Burglar or Fire Alarms, Electric Gas 
Lighting Apparatus, Electric 
Heat Regulating Appa¬ 
ratus, etc., etc. 


THE ONLY BOOK OF THE KIND PUBLISHED, 

Sent, Postage Free, on Receipt of Price. 


Electrician Publishing Comp’y, 

6 Lakeside Building, Chicago, 




Eugene F. Phillips, Pres. 


W. H. Sawyer, Secy, 


^merieari Electrical Works, 

PROVIDENCE, R, I„ 

MANUFACTURERS OF 

Faraday * Gable, 

PATENT FINISHED INSULATED 

Electric Light Wires, 
Weatherproof Line Wire, 

Patent Rubber Covered Wire, 
Incandescent Lamp Cord, 

Maghbt Wirb, 

LEAD ENCASED WIRE. 


New York Office, 18 Cortlandt Street, 

F. C. ACKEFMAN, Agent. 



Detroit Storage Battery, 

After careful Improvements in construction, lias now been 
found to be Thoroughly Reliable and Durable, 
and is, owing to its design, Peculiarly Adapt¬ 
ed to many uses in which other types 
of batteries have failed. 


•SPECIALLY ADAPTED TO 


Central Station Lighting, 
Street Cars, 

Burglar Alarms, 
DrivingVentilating Fans, 
Sewing Machines, etc.. 
Operating Signal Bells on 
Cars, 


Steadying Lights, 
Propelling Boats, 
Isolated Lighting, 
Auxiliary Central Station 
Work, 

Medical Purposes, 
Running of Small Motors. 



It is positively the only Secondary Battery which will not 
Buckle, or which will withstand uninjured the Highest 
Rates of Discharge. 


MANUFACTURED AND FOR SALE BY 

The Woodward Electrical Co., 

DETROIT, MICH. 

OFFICES, FACTORY, 

69 Griswold St., Campau Bldg. Cor. 13th and Howard Sts, 























established in 1861 . 

E. BAGGOT, 


WHOLESALE AND RETAIL DEALER IN 

ELECTROLIERS, 



Combination 

AND 

ELECTRIC 

■ FIGURES, 

ELECTRIC 

GLOBES, 

SHADES, 

ETC., ETC. 

Madison St. & Fifth Ave. 
CHICAGO 


BRANCH STORE, 

2134 Michigan Aue. 













M. T. Greene, Pres. Geo A. McKinlock, Treas. 

Wm. II. McKinlock, Secretary. 

Central Electric Companj, 

42 LA SALLE STREET, 

CHICACO, 

Manufacturers, Importers and Dealers in 

ELECTRIC LIGHT, 

TELEPHONE, 

TELEGRAPH , 

ELECTRIC RAILWAY, 

AND BELL-HANGERS’ SUPPLIES. 



GENERAL WESTERN AGENTS 

Candee Weather-Proof Wire, The Butler Hard 
Rubber Co., Lockwood Polarity Indicator, 
Cleveland’s Switches and Cut-Outs, 
Fletcher’s Sleet - Proof Pulleys, Detroit Storage 
Battery, Parrish Bros. & Peck Train and 
Boat Signal, The Eddy Motor and 
Electro-plating Machine. 







Charles A Cmeever, Pres. Willard L. Candee, Treas. 
Cazenove Jones, General Superintendent. 

THE 0K0N1TE CO., 

No. 13 Park Row, NEW YORK. 



TRADE MARK. 


MANUFACTURERS OF IMPROVED 

INSULATED 

U/lF^5?QlBlE5. 

Those who have used OKONITE Wires and Cables, are unani¬ 
mous in their declarations that OKONITE is the best 
insulating medium in Ihe market. For 
DURABILITY and TOUGHNESS 
the OKONITE WIRES 
are unexcelled. 

SOLE MANUFACTURERS OF 

candee aerial wires, 

OKONITE WATERPROOF TAPE, 
MANSON PROTECTING TAPE. 

BRANCHES: Boston, Philadelphia, Chicago, St. 
Louis, Minneapolis, Kansas City, Louisville, Cin¬ 
cinnati and San Francisco. 



TBOMSOMOUSTON 

El<?etri<; Qompapy, 

620 Atlantic Ave., 148 Michigan Ave., 

BOSTON, MASS., CHICAGO, ILLS., 

MANUFACTURERS OF 

Arc Light Systems, 

Direct Incandescent Electric Light Systems, 
Alternating Incandescent Systems , 
Electric Motors, Electric Railways. 


This Company maintains at all times a skilled corps of 
'men in its Incandescent Department for the purpose of 
wiring buildings for electric lights. Estimates furnished 
for complete installations upon application. 



BEFORE PURCHASING 

-FOR YOUR—- 

Electric Light Plant, 

Electric Power Plant, 

Electric Railway, 

Write for our Illustrated Catalogue and examine quality of 

our Goods 

--WE MANUFACTURE- 

Wires and Cables of Every description. Flexible 
Cords, Testing: Instruments, Tools, 
Construction Material. 

-We TATisli to Remind- 

Contractors and Electric Light Companies 

That our whole time and attention is employed in 
manufacturing for and attending to 
their wants. 

We Never Undertake Construction Work, 

We Have No Electric Light System, 

-AND THEREFORE- 

Never Conflict With Our Customers’ Interests. 


It Will Pay You to Write us Fully Before 
Purchasing Elesewhere. 


The Electrical Supply Co., 

171 RANDOLPH STREET, CHICAGO, ILL. 


FACTORIES : Ansonia, Conn. 

















































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